Issued November 7, 1911. 

>0RT0 RICO AGRICULTURAL EXPERIMENT STATION, 

D. W. MAY, Special Agent in Charge. 

Mayaguez, May, igxt. 



Bulletin No. 11. 



RELATION OF CALCAREOUS SOILS 
TO PINEAPPLE CHLOROSIS. 



P. L. GILE, 

CHEMIST. 



UNDER THE SUPERVISION OF 
OFFICE OF EXPERIMENT STATIONS, 

U. S. DEPARTMENT OF AGRICULTURE. 



WASHINGTON: 
GOVERNMENT PRINTING OFFICE. 

1911. 



Honocraph 



Bui. II, Porto Rico Agr. Expt. Station. 



Frontispiece. 




1377 

Issued November 7, 1911. 

PORTO RICO AGRICULTURAL EXPERIMENT STATION, 

D. W. MAY, Special Agent in Charge. 

Mayaguez, May, ign. 



Bulletin No. 11. 



RELATION OF CALCAREOUS SOILS 
TO PINEAPPLE CHLOROSIS. 



P. L. GILE, 

CHEMIST. 



UNDER THE SUPERVISION OF 
OFFICE OF EXPERIMENT STATIONS, 

U. S. DEPARTMENT OF AGRICULTURE. 



WASHINGTON: 

GOVERNMENT PRINTING OFFICE. 

1911. 



C^Wm £ 



oe> 



^ 
v 



^ 



<? 



PORTO RICO AGRICULTURAL EXPERIMENT STATION. 

[Under the supervision of A. C. True, Director of the Office of Experiment Stations, United States Depart- 
ment of Agriculture.] 

Walter H. Evans, 
Chief of Division of Insular Stations, Office of Experiment Stations. 

STATION STAFF. 

D. W. May, Special Agent in Charge. 
Oscar Loew, Physiologist. 

W. V. Tower, Entomologist. 
P. L. Gile, Chemist. 
G. L. Fawcett, Plant Pathologist. 
C. F. Kinman, Horticulturist. 

E. G. Ritzman, Animal Husbandman. 

T. B. McClelland, Assistant Horticulturist. 
C. X. Ageton, Assistant Chemist. 
W. E. Hess, Expert Gardener. 
Carmelo Alemar, Jr., Stenographer. 



W % 



*=s 



LETTER OF TRANSMITTAL. 



Porto Rico Agricultural Experiment Station, 

Mayaguez, Porto Rico, May 1, 1911. 
Sir: I have the honor to transmit herewith a manuscript on the 
subject of Relation of Calcareous Soils to Pineapple Chlorosis. Owing 
to the great increase in importance of this fruit in Porto Rico any 
investigation leading to its improvement is timely. The number of 
failures occurring in certain soils which apparently are well adapted 
to pineapple growing lends value to the results as set forth in this 
manuscript, which offers an explanation of the cause of the failures 
and suggests means of avoiding great losses in the future. 

I respectfully recommend that this manuscript be issued as Bulletin 
No. 11 of this station and that it be published in both English and 
Spanish. 

Respectfully, D. W. May, 

Special Agent in Charge. 
Dr. A. C. True, 

Director Office of Experiment Stations, 

V. S. Department of Agriculture, Washington, D. C. 

Recommended for publication. 
A. C. True, Director. 

Publication authorized. 
James Wilson, 

Secretary of Agriculture 
LBull. llj (3) 



CONTENTS 



Page. 

Introduction 5 

History of plantings on unsuitable soils 5 

Appearance of plants on unsuitable soils 6 

Preliminary investigations 6 

Investigations of pineapple soils 8 

Chemical survey of the pineapple soils of Porto Rico 8 

Pineapple soils of other countries 18 

Pot experiments with different types of soil 20 

Experiments with plants grown in small field plats 26 

Conclusions from soil investigations 27 

Investigations of the chlorosis 29 

Previous work on lime-induced chlorosis 29 

Effect of soil alkalinity and assimilable lime in causing chlorosis 31 

Treatment of chl orotic plants with iron and other salts 32 

Ash content of green and chlorotic leaves 34 

Enzyms in chlorotic and green leaves 39 

Effect of light on the chlorosis 42 

Conclusions from investigations of the chlorosis 43 

Summary 44 

Acknowledgment 45 



ILLUSTRATIONS 



Page. 
Plate I. Normal green plant and two stages of chlorosis Frontispiece. 

II. Fig. 1. — Effect of carbonate of lime on the growth of pineapples. 

Fig. 2. — Effect of ferrous sulphate on chlorotic pineapple plants. ... 22 

I Bull, ll] (4) 



RELATION OF CALCAREOUS SOILS TO PINEAPPLE 

CHLOROSIS. 



INTRODUCTION. 
HISTORY OF PLANTINGS ON UNSUITABLE SOILS. 

Raising pineapples on a commercial scale is a comparatively new 
but rapidly growing industry in Porto Rico. As more and more land 
is being planted to pineapples it is becoming apparent that all of the 
loose, well-drained soils are not adapted to this crop. On certain 
well-drained soils of good physical condition the pineapple plantings 
have been very unsuccessful. The failure of these plantings has been 
attended by a peculiar " bleaching" or chlorosis ' of the plants, in some 
cases so complete that the leaves contain hardly a trace of chlorophyll. 

The investigation detailed in the following pages was undertaken 
for the purpose of discovering the cause of the chlorosis and the failure 
of the crop on these soils. 

The first instance of the plants presenting this peculiar bleached 
appearance on a well-drained soil was noted at Rincon, P. R., by Mr. 
H. C. Henrieksen in 1904, and is described in the annual report of this 
station for 1905 : 2 

In the fall of 1903 about 2 acres were planted at Rincon with the variety Cabezona. 
The plants were reported to be diseased and the field was visited April, 1904, at the 
owner's request. The plants were found to be of normal size, but the color of the 
leaves was of a light red to pure wax white, about 50 per cent being entirely devoid of 
chlorophyll and less than 15 per cent showing green, the rest red, green, and white 
mixed. The field was located near the ocean, but in no way injured by salt water. 
The soil, which was a beach sand, had recently been cleared of its natural growth, 
consisting mainly of coconut, sea grape, coco plum, a few sour orange trees, and the 
usual tropical shore-line plants. 

Since this case was reported numerous other instances of pine- 
apples showing the same appearance have been noted. On two 
plantations, of about 10 acres each, the plants became almost uni- 
formly yellowish white and ultimately succumbed. About 60 per 

1 Chlorosis (sometimes called " icterus," "bleaching," or " Gelbsucht") is the term applied to that con- 
dition assumed by the leaves of plants when they fail to develop the normal amount of chlorophyll, or 
green coloring matter, i. e., when they are yellowish or white instead of a normal green. Chlorosis, then, 
does not denote a specific disease, but merely a general condition. This condition of chlorosis, however, is 
the result or outward sign of a disease or disturbance in the physiology of the plant. To say that a plant 
is "chlorotic," or affected with chlorosis, means merely that its leaves are lacking in chlorophyll; but the 
chlorosis may have resulted from a bacterial disease, poor drainage, lack of nutriment, or some other cause. 

2 Porto Rico Sta. Rpt. 1905, p. 30. 

[Bull. 11] (5) 



cent of the plants in another 10-acre field are now affected the same 
way. Several fields of 1 or 2 acres with the same symptoms have 
been lost, and numerous cases of a few hundred plants showing this 
peculiar chlorosis have been observed in different plantations. 

The places where the chlorotic plants occurred were not confined to 
any one district of the island or to any one physical type of soil. 

APPEARANCE OF PLANTS ON UNSUITABLE SOILS. 

The degree to which the plants were affected and the age of the 
plants when the bleaching first manifested itself varied somewhat in 
the different instances. In some places many plants became almost 
ivory white, apparently without a vestige of chlorophyll; later the 
leaves of such plants showed brown spots and the plants finally 
decayed. In other cases the leaves were a yellowish wlrite, with red 
streaks and small patches of green. Sometimes the outer leaves 
remained a light green while the new heart leaves were creamy white. 
In other cases the leaves were for many months practically normal 
in color, but gradually light spots appeared, producing a mottled 
appearance, and finally, in 14 or 15 months, the leaves bleached out to 
a uniform greenish yellow. The lack of chlorophyll, or chlorosis, 
was generally very pronounced when the plant was 9 months old, 
though sometimes it appeared in 3 or 4 months, and sometimes it did 
not appear until the plant was 15 or 16 months old. 

The root system of the chlorotic plants showed no evidence of 
disease. The roots differed from those of normal plants in being 
somewhat longer and not so thick; they were more like those of plants 
suffering from starvation. The plants, however, that had suffered 
from the chlorosis for some time had many dead roots, but the func- 
tioning roots appeared to be perfectly healthy and on examination by 
the pathologist failed to show any bacterial or fungus trouble. 

PRELIMINARY INVESTIGATIONS. 

From the fact that the first examples of the chlorosis appeared in 
plantations near the sea it was thought by some that the trouble was 
caused by sea spray being blown in on the plants. Tins was shown 
not to be the case, however, as on some plantations within less than 
a hundred yards of the sea the plants were perfectly green and 
healthy and later the distinctive chlorosis was observed on planta- 
tions several miles from the coast ; moreover, plants heavily sprayed 
with sea water for four consecutive days showed no injury. 

It was also thought that the chlorosis might be attributed to lack of 
aeration of the roots from poor drainage. In some places where the 
chlorosis occurred the drainage was poor, and in the spots of poorest 
drainage the chlorosis was most intense. In other places, however, 

LBull. 11] 



plants on loose, sandy soils of perfect drainage became strongly chlo- 
rotic. It was thus apparent that although the trouble was intensi- 
fied by poor drainage, faulty drainage was not the primary cause. 

The appearance of patches of chlorotic plants in the midst of 
fields that were for the most part green and vigorous made it seem 
probable that it was a bacterial disease. But investigations by the 
pathologist failed to reveal any bacterial or fungus disease. The 
fact that chlorotic plants on transplanting to different soils in every 
case recovered also militated against this view. Chlorotic plants and 
soil were secured from three different plantations and placed in pots. 
The chlorotic plants in the original soil in all cases remained without 
change, while those placed in a river sand became, in a short time, 
green and healthy. Also, since these investigations were started 6 
acres of chlorotic plants have been taken up and set out in soil of a 
different character. Here they became green within a month or two, 
and, in the year that has elapsed since transplanting, not a single 
plant has developed the chlorosis. Had the plants been infested with 
bacteria or fungi they could hardly have shown such a uniform 
recovery on transplanting to different soils of a similar physical 
character. 

Experiments with commercial fertilizers and stable manure were 
tried in 1904 and 1908 by the horticulturist on two of the plantations, 
where the chlorosis was very marked, to see whether the trouble could 
have been caused by lack of nutriment. 

It was found that although the complete fertilizers improved the 
condition of the plants slightly, they were without much effect. The 
stable manure produced slightly more improvement than the com- 
mercial fertilizers. 

It being, then, seemingly impossible that the chlorosis could have 
been produced by disease, lack of nutriment, poor drainage, or injury 
from the sea, it was thought probable that the cause was to be found 
in the unsuitable chemical character of the soil. Accordingly, soils 
were collected from all the areas where the chlorosis occurred and 
from adjacent fields where the pineapples were doing well. In some 
cases patches of a few hundred chlorotic plants occurred in the midst 
of several acres of healthy green plants. Hence, it was to be expected 
that, if the trouble was due to the chemical character of the soil, a 
difference would be apparent in the analyses of the soils where the 
healthy and unhealthy plants were growing. In addition to such 
comparative analyses, analyses were made of most of the well-drained 
soils where pineapples were growing well. It was thought that, 
should the soils producing chlorotic plants show a chemical character 
that adjacent areas with healthy plants did not, and should none of 
the good pineapple soils show the same characteristics as the bleached 
areas, the specific cause would become apparent. 

[Bull. 11] 



8 

INVESTIGATIONS OF PINEAPPLE SOILS. 
CHEMICAL SURVEY OF THE PINEAPPLE SOILS OF PORTO RICO. 

The individual cases where chlorotic pineapples were found are 
described below. The analysis of the soil is given in each case, 
together with that of adjacent areas where pineapples grow well. 

The samples were all taken from the first 8 inches of soil, as in this 
part of the soil practically all the pineapple roots are found. The 
analyses were made by digestion with hydrochloric acid of specific 
gravity 1.115 according to the official methods of the Association of 
Official Agricultural Chemists. The carbon dioxid was determined 
by absorption and from this the percentage of calcium carbonate 
calculated. This does not give a strictly accurate determination 
of the lime present as carbonate, inasmuch as it fails to distinguish 
between calcium and magnesium carbonate. For the purpose, 
however, the method suffices. The oxids of lime and magnesia were 
of course exactly determined in the acid digestion. 

All of the following samples were tested for water soluble alkaline 
salts and chlorids, but none was found present. The alkaline reaction 
of certain of the soils is due to the presence of the carbonates of lime 
and magnesium. 

SOIL SURVEY I. 

Plantation (Isla Verde) of Mr. Noble, about 5 miles east of San- 
turce, P. R.: Here there were 10 acres of Red Spanish pineapples 
on a loose, well-drained, gray sand, a few hundred yards from the sea. 
The surrounding vegetation consisted of icacos, Santa Maria, roble, 
and leguminous weeds and low growing bushes. In 9 or 10 months 
the plants had all become chlorotic with the exception of a 2-acre 
patch at one corner of the field and a few scattered individuals. The 
few isolated plants later lost their color, w T hile in the 2-acre patch 
they did not lose their green color up to the time of fruiting and 
produced fruit of sizes 18, 24, and 36 at the rate of 300 boxes per acre. 
The plants were fertilized at various times with a complete pineapple 
fertilizer. 

A year after planting, about 6 acres of chlorotic plants were taken 
up and set out in a field a quarter of a mile farther inland on a reddish 
sandy soil, of finer texture than that of the original field. The plants 
soon recovered their normal green color and have continued to grow 
well without showing any chlorosis. 

Below are given the soil analyses. Samples 101 and 102 were 
taken from patches where the plants became chlorotic; No. 79 is the 
subsoil beneath chlorotic plants; No. 132 is from the corner of the 
field where the chlorosis failed to appear; No. 152 is a sample from 
the field to which the plants were transplanted with a complete 
recovery. 

[Bull. 11] 



Analyses of pineapple soils. 



Soil constituents and reactions. 



Insoluble matter 

Potash ( K 2 0) 

Lime (CaO) 

Magnesia (MgO) 

Ferric and al;iminicoxids(Fe20s andAhOs) 

Phosphorus pentoxid (P2O5) 

Volatile matter 



Total. 



Nitrogen (N) 

Moisture 

Carbon dioxid (CO2) 

Calcium carbonate (CaCCh)- 
Reaction to litmus 



No. 79. 

(plants 

chlorotic). 



Per cent. 

54.04 

.06 

22.27 

2.01 

.79 

.04 

20.79 



100.00 



.02 
1.37 



Alkaline. 



No. 101. 

(plants 

chlorotic). 



Per cent. 

56.85 

.03 

20.40 

.78 

2.06 

.05 

19.87 



100. 04 



.12 

4.01 

14.88 

33.85 

Alkaline. 



No. 102. 

(plants 

chlorotic). 



Per cent. 

56.69 

.03 

19.54 

.86 

2.12 

.06 

21.23 



100. 53 



.22 

4.42 

14.14 

32.17 

Alkaline. 



No. 132. 

(plants 

healthy). 



No. 152. 

(plants 

healthy). 



Trace. 

Trace. 

Alkaline. 



Per cent. 

89.76 

.08 

.15 

.77 

5.70 

.03 

3.10 



99.65 



.06 

.43 

Trace. 

Trace. 

Neutral. 



It will be seen by the above analyses that the soils where the plants 
became chlorotic contain a large amount of carbonate of lime, that 
the soil where the plants remained healthy contains a trace, and that 
the soil where the chlorotic plants recovered contains but little lime and 
no carbonate of lime. 

SOIL SURVEY II. 

Plantation of the Bird Bros, at Luquillo: This planting of Red 
Spanish pineapples consisted of about 10 acres or more; it was on a 
loose sandy soil a few hundred yards from the sea. The pineapples 
were planted between coconut trees. The soil was of good physical 
condition, but the land was so low that the drainage was poor. After 
very heavy rains the water was found standing within 12 inches of the 
surface. 

The chlorosis here was more marked than on any other plantation. 
When 6 or 8 months old most of the plants were waxy white. At the 
end of 18 months many plants were dead, the greater part of the 
remainder were colorless, while a few were of a light green with long 
spiky leaves. About a dozen plants with very small fruits were found. 
On no part of this field were the plants vigorous. The analyses of sam- 
ples of soil taken from various parts of the planting are given below : 
Analyses of pineapple soils (plants chlorotic) . 



Soil constituents and reaction. 



No. 163. 



No. 191. 



No. 194. 



Insoluble matter 

Potash ( K 2 0) 

Lime (CaO) 

Magnesia ( MgO ) 

Ferric and aluminic oxids (Fej03 and AI2O3) 

Phosphorus pentoxid ( P2O5) 

Volatile matter 

Total 

Nitrogen (N) 

Moisture 

Carbon dioxid (CO2) 

Calcium carbonate (CaCOs) 

Reaction to litmus 



Per cent. 
7.84 
.19 
44.73 
2.26 
3.16 
.16 
42.25 



Per cent. 
3.53 



Per cent. 
3.13 



43.49 

1.43 

4.71 

.17 

45.87 



42. 94 

5.78 

3.08 

.20 

44.29 



100. 59 



.20 

1.78 

35.03 

79.70 

Alkaline. 



.19 

1.70 

33.55 

76.33 

Alkaline. 



.27 

1.90 

35.06 

79.76 

Alkaline. 



412°— Bull. 11—11- 



10 

This is a coralline sand, evidently formed by the sea grinding down 
coral reefs. It will be seen that although it is fairly rich in nitrogen, 
potash, and phosphoric acid it is excessively calcareous, like the bad 
soils in Survey I. The trouble here, however, was complicated by 
poor drainage. 

SOIL SURVEY III. 

Plantation of Mr. Mathews at Rincon, P. R. : This is the plantation 
described on page 5. In 1910 the field was visited by the writer. 
The plants had been removed some years previous, but a few plants 
were found which were of fair size, although practically colorless. A 
soil sample, No. 224, was taken near these plants. 

In the vicinity 6 or 7 plants of the native variety Caraquefla were 
found growing. Two of these plants were very small and almost 
pure white ; the others were of fair size with very light green narrow 
leaves. The soil sample from near the roots of these plants is No. 225. 

A quarter of a mile farther on a small patch of about a hundred 
Cabezonas and Caraquerias were found growing. All the plants 
were of small size and light-greenish yellow or yellow- white in color. 
A few plants were bearing dwarfed fruits. The soil from this spot 
is designated as No. 226. The soil in these three cases was of the 
same character, a coarse, well-drained, beach sand with a fair amount 
of organic matter. Coconuts, oranges, and gandules or pigeon peas 
seemed to grow well here. 

Analyses of pineapple soils (plants chlorotic). 



Soil constituents and reaction. 



No. 224. 



No. 225. 



No. 226. 



Insoluble matter 

Potash ( K 2 ) 

Lime (CaO) 

Magnesia (MgO) 

Ferric and aluminic oxids (Fe203 and AI2O3) 

Phosphorus pentoxid ( P2O5) 

Volatile matter 

Total 

Nitrogen (N) 

Moisture 

Carbon dioxid (C0 2 ) 

Calcium carbonate (CaCOs) 

Reaction to litmus 



Per cent. 

70.15 

.09 

11.77 

.36 

4.06 

.09 

12.95 



Per cent. 
67. 63 
.09 
12.40 
1.07 
4.52 
.16 
13.29 



99.47 



99.16 



.09 

.69 

7.93 

18.04 

Alkaline. 



.10 

.76 

9.57 

21.77 

Alkaline. 



Per cent. 
75.36 
.09 
8.28 
5.20 
5.20 
.12 
10.80 



100.12 



.16 
1.00 
6.29 
14.31 

Alkaline. 



These soils are slightly richer in potash and phosphoric acid than 
in Survey I and not so high in lime, but they are still to be regarded 
as strongly calcareous. 

SOIL SURVEY IV. 

Property of Mr. William Gay, Dorado, P. R.: Here about 2 acres 
of red Spanish pineapples were set out on a sand near the sea. The 
soil was of good physical character with considerable organic matter, 

[Bull. 11] 



11 

but so low that during heavy rains the ground water approached the 
surface. Most of the plants did fairly well, but a strip about 10 
yards wide, running transversely across the field, exhibited the char- 
acteristic chlorosis, having ivory white leaves with small patches of 
green. The field had been fertilized with stable manure. Citrus 
fruits and gandules grew exceptionally well on this plantation. Sam- 
ple 148 is of the soil where the pineapples were healthy, and 149 is 
from a patch of chlorotic plants. These samples were taken by one 
of the station staff. Sample 154 is another sample of the bad soil 
and 155 of the good soil sent in by Mr. Ga}^. The samples of good 
and bad soil were taken only a few yards apart. 

Analyses of pineapple soils. 



Soil constituents and reaction. 



No. 148 

(plants 

healthy). 



No. 149 

(plants 

chlorotic). 



No. 154 

(plants 

chlorotic). 



No. 155 

(plants 

healthy). 



Insoluble matter 

Potash (K 2 C ) 

Lime (CaO) 

Magnesia (MgO) 

Ferric and aluminic oxids (Fe 2 3 and AI2O3) 

Phosphorus pentoxid ( P2O5) 

Volatile matter 

Total 

Nitrogen (N) 

Moisture 

Carbon dioxid (CO2) 

Calcium carbonate (CaCOs) 

Reaction to litmus 



Per cent. 

93.28 

.07 

1.92 

.14 

.51 

.04 

4.12 



100. 08 



.58 

.50 

1.14 

Alkaline. 



Per cent. 

44.02 

.04 

22.19 

2.50 

2.31 

.09 

27.84 



Per cent. 

63.19 

.32 

16.02 

1.58 

1.59 

.07 

18.16 



98.99 



100. 93 



.30 

.27 

16.96 

38.56 

Alkaline. 



.22 

3.30 

10.69 

24.32 

Alkaline. 



Per cent. 

93.17 

.22 

1.00 

.37 

.91 

.02 

3.51 



99.20 



.11 

1.07 

.09 

.20 

Alkaline. 






It will be seen that 149 is, on the whole, richer in plant food than 148 
but that the bad soil is here again strongly calcareous while the good 
soil has but little calcium carbonate. The same difference is true of 
154 and 155. The calcium carbonate in the bad soil plainly originated 
from disintegrated coral. 

SOIL SURVEY V. 

Property of Mr. Piza, Dorado, P. R. : This plantation consisted of 
about 30 acres of red Spanish pineapples. The greater part of the 
plants were on a white, almost pure silica sand; the rest of the plants 
were on a red clay of varying stiffness. Only two patches of chlo- 
rotic plants were found. These were growing in a fairly stiff loam 
on a hill near the seashore. In one spot there were three small 
plants almost ivory white in color. These were surrounded by large 
vigorous plants of a dark-green color. Sample 197 is taken from 
about the roots of the white plants. The soil here, however, was 
only 3 inches deep, and the roots of the plants were directly on the 
surface of the coral rock; there were numerous coral nodules in the 

I Hull. 11] 



12 

soil. Sample 198 was taken from a patch of exceptionally vigorous 
plants 10 yards away. About 100 yards distant was another patch 
of 50 colorless plants. The soil, of which No. 199 is a sample, con- 
tained many coral particles but was over 2 feet deep. No. 200 was 
taken from the midst of vigorous plants 15 yards distant from No. 
199. The soil here contained no coral particles. Twenty-five per 
cent of sample 197, 4 per cent of 198, and 40 per cent of 199 did not 
pass through a 1 millimeter sieve. This residue that is not included 
in the analyses was made up of coral particles, i. e., calcium car- 
bonate. Hence the soil in these three cases must be regarded as con- 
taining more calcium carbonate than appears in the analyses. 

Analyses of pineapple soils. 



Soil constituents and reaction. 



No. 197 

(plants 

chlorotic). 



No. 198 

(plants 

healthy). 



No. 199 

(plants 

chlorotic). 



No. 200 

(plants 

healthy). 



Insoluble matter .' 

Potash (K 2 0) 

Lime(CaO) 

Magnesia (MgO) 

Ferric and aluminic oxids (Fe203 and AI2O3) 

Phosphorus pentoxid (P2O3) 

Volatile matter 

Total 

Nitrogen (N) 

Moisture 

Carbon dioxid (C0 2 ) 

Calcium carbonate (CaCOs) 

Reaction to litmus 



Per cent. 

73.91 

.20 

5.17 

Trace. 

9.24 

1.13 

11.65 



100.30 



.40 

3.32 

2.03 

4.62 

Alkaline. 



Per cent. 

83.08 

.24 

1.44 

.42 

6.03 

.09 

8.71 



Per cent. 

79.43 

.24 

3.41 

.38 

6.66 

.08 

8.93 



100.01 



99.13 



.29 

4.10 

.00 

.00 

Alkaline. 



.22 

3.34 

2.22 

5.05 

Alkaline. 



Per cent. 

81.74 

.24 

1.50 

.25 

9.61 

.08 

6.50 



99.92 



.18 

3.30 

Trace. 

Trace. 

Alkaline. 



Here again the difference between the good and bad soils, lying in 
such close proximity to each other, is in the content of calcium 
carbonate. 

SOIL SURVEY VI. 

Plantation of Arturo S. Jimenez (Plantage del Rio) about 3 miles 
west of Bayamon: Of about 2 acres of red Spanish pineapples planted 
here 90 per cent had lost their color within 12 months. Six months 
later the remaining 10 per cent became colorless and the plants were 
removed. The planting was located a mile or more distant from the 
sea on a loose, sandy soil that contained many shell particles, 
Bananas and native corn were growing fairly well here. Previous 
to planting with pineapples a good crop of tobacco had been taken 
from this field. Samples 183 and 185 were taken from two different 
parts of the field by the writer; No. 156, from the same field, was 
taken by a neighboring planter. No. 157 is a sample from a nearby 
healthy planting and was taken by the owner. 

[Bull. 11] 



13 



Analyses of pineapple soils. 



Soil constituents and reaction. 



No. 183 

(plants 

chlorotic). 



No. 185 

(plants 

chlorotic). 



No. 156 

(plants 

chlorotic). 



No. 157 

(plants 

healthy). 



Insoluble matter 

Potash (K 2 ) 

Lime (CaO) 

Magnesia (MgO) 

Ferric and aluminic oxids (Fe20 3 and AI2O3) 

Phosphorus pentoxid ( P2O5) 

Volatile matter 

Total 

Nitrogen (N) 

Moisture 

Carbon dioxid (CO s ) 

Calcium carbonate (CaCC>3) 

Eeaction to litmus 



Per cent. 

70.26 

.13 

10.47 

.74 

7.58 

.18 

11.35 



Per cent. 

73.07 

.12 

8.27 

1.12 

7.42 

.21 

10.18 



Per cent. 
67.15 



11.42 

1.17 

9.57 

.07 

12.41 



100.71 



100.39 



.11 

4.60 

7.15 

16. 27 

Alkaline. 



.11 


.16 


1.89 


1.95 


5.18 


6.66 


11.78 


15.15 


Alkaline. 


Alkaline. 



Per cent. 

82.13 

.10 

2.01 

.21 

8.77 

.29 

7.33 



100.85 



.21 

5.44 

None. 

None. 

Alkaline. 



The three soils producing chlorotic plants are very similar to the 
soils in Survey III and are strongly calcareous, while the good soil 
(No. 157) differs only in containing no calcium carbonate. 



SOIL SURVEY VII. 

Plantation of Golden Fruit Co., about 3 miles from Bay anion: At 
various times about 40 acres were planted with Red Spanish pine- 
apples. About half the acreage produced remarkably large plants 
that bore a good crop of large-sized fruit. Most of the plants were 
fertilized with a complete commercial fertilizer and a few received 
some barnyard manure. The soil of these fields was a loose, loamy 
sand with considerable organic matter and is represented by samples 
186 and 187. 

Another field of about 20 acres was planted in the fall of 1909. A 
year later about 50 per cent of the plants had lost most of their green 
color and many had died. The 50 per cent that were unaffected 
were of normal dark green and were distributed in irregular patches 
throughout the field. The soil in this case was a loose sand that in 
spots contained many shell particles. Sample 229 was taken from 
a patch of colorless plants and 230 from an area a few yards distant, 
where the plants were green. It was observed that wherever in the 
field the soil contained many shell particles the plants were chlorotic 
and where these particles were absent the plants were green. The 
soil also was tested in many places with acid, and wherever the 
chlorotic plants were found the effervescence showed the presence of 
carbonate of lime, while wherever the green plants were found there 
was no effervescence,, 

[Bull. 11] 



14 

Analyses of pineapple soils. 



Soil constituents and reaction. 



Insoluble matter 

Potash (K 2 0) 

Lime (CaO ) 

Magnesia (MgO) 

Ferric and aluminic oxids (Fe2C>3 and 

AI2O3) 

Phosphorus pentoxid (P2O5) 

Volatile matter , 



Total. 



Nitrogen (N) 

Moisture 

Carbon dioxid (C0 2 ) 

Calcium carbonate (CaCC«3). 
Reaction to litmus 



No. 231 

(plants 

chlorotic). 



Per cent. 
79.54 



2.45 
Trace. 

9.20 
.17 

7.85 



.20 
2.30 

.82 

1.86 

Alkaline. 



No. 186 

(plants 

healthy). 



Per cent. 

79.01 

.12 

4.25 

.17 

9.50 

.12 
7.42 



100. 59 



.20 

1.93 

.24 

.57 

Alkaline. 



No. 187 

(plants 
healthy). 



Per cent. 

83.37 

.10 

.97 

Trace. 

7.44 

.09 

7.19 



99.16 



.20 

5.77 

.00 

.00 

Alkaline. 



No. 229 
(plants 

chlorotic). 



Per cent. 

80.97 

.16 

3.57 

.77 

8.24 

.11 

6.53 



100. 36 



.14 

1.45 

1.50 

3.41 

Alkaline. 



No. 230 

(plants 

healthy). 



Per cent. 

81.12 

.17 

1.36 

Trace. 

11.56 

.13 

6.48 



100. 82 



.19 

2.27 

None. 

None. 

Alkaline. 



Soil No. 186, producing fine plants, contains much lime, but only a 
small amount of carbonate of lime. No. 187, a good soil, contains 
no carbonate of lime. No. 230, also good, contains no carbonate of 
lime, whereas Nos. 229 and 231, the bad soils, contain much carbonate. 



SOIL SURVEY VIII. 

Plantation of Sucesores de Frontera, to the north of Mayaguez 
playa: About 2 acres were planted with Cabezona pineapples in a 
coconut grove bordering the shore. The soil was a loose sand, but 
so low that the drainage was poor. About 30 per cent of the plants 
grew to maturity and bore fruit. The leaves of these plants were 
green, but narrow and spiky. Many of the other plants died or had 
light green and yellow leaves; there were only a few ivory-white 
plants. The drainage being poor and the plants not well cared for, 
no conclusion could fairly be drawn from this case alone. No. 233 
is a sample from this field. 

On the south side of Mayaguez Bay there are numerous plantings 
of Red Spanish and Cabezona pineapples in 2 and 4 acre patches. 
No examples of chlorotic plants were found there. Considering that 
most of the fields are unfertilized the plants have done fairly well. 
The soil is sandy, but of *a different character and origin from that on 
the opposite side of the bay; No. 232 is a sample. The soil at the 
south is apparently an alluvial deposit and very old, containing no 
calcium carbonate, while the soil on the opposite shore, where the 
chlorotic plants were found, contains many coral and shell particles 
and was recently built up by the sea. 

[Bull. 11] 



15 

Analyses of pineapple soils. 



Soil constituents and reaction. 



Insoluble matter 

Potash (K 2 0) 

Lime (CaO) 

Magnesia (MgO) 

Ferric and aluminic oxids (Fe203 and AI2O3) 

Phosphorus pentoxid (P2O5) 

Volatile matter 

Total 

Nitrogen (N) 

Moisture 

Carbon dioxid (CO2) 

Calcium carbonate (CaCOs) 

Reaction to litmus 



No. 232 

(plants 

healthy). 



Per cent. 

63.40 

.09 

2.44 

5.67 

18.86 

.09 

7.11 



97. 0(3 



.06 

1.59 

None. 

None. 

Neutral. 



No. 233 

(plants 

chlorotic). 



Per cent. 

77.64 

.10 

5.00 

Trace. 

8.05 

.15 

8.45 



99.09 



.12 
9.95 
1.45 
3.30 

Alkaline. 



Here again we find the good soil devoid of calcium carbonate, 
while the bad soil is calcareous and poorly drained. 



SOIL SURVEY IX. 

Near the road from Rio Piedras to Carolina there are several 
patches of pineapples showing the characteristic chlorosis. The 
size of these spots varies from an acre to 200 plants, and they occur 
on four different plantations. As they are all similar, they will be 
considered together. The soil on both sides of the road is for the 
most part a silicious sand well suited for pineapples, as is evidenced 
by the large acreage and the uniform success of the plantings. 

Directly bordering on the road, however, some patches of yellow 
and white plants were observed. The soil in these spots when tested 
with acid effervesced strongly, showing the presence of much car- 
bonate of lime. The soil in the immediate neighborhood, where 
healthy plants were found, gave no effervescence. A large number 
of spots in the different fields where healthy plants were growing 
were tested, and in no case was carbonate of lime present. 

The road on which these plantations border is constructed of lime- 
stone rock. In the construction and maintenance of this road 
limestone rock was piled in the fields alongside and there pulverized. 
During the pulverization much carbonate of lime was incorporated 
in the soil. It seems that this is the origin of such small areas of 
calcareous soil as occur in the silicious sand. 

Messrs. De Sola and Wolf, at kilometer 9, have about an acre of 
chlorotic plants. Samples 204 and 205 were taken from the bleached 
area and samples 207 and 208 from adjacent green areas. The 
plants in the bleached area are exposed to the effect of more car- 
bonate of lime than appears from the soil analyses, since the drainage 
water from the road runs down over this spot. 

[Bull. 11] 



16 



Analyses of pineapple soils. 



Soil constituents and reaction. 



No. 204 

(plants 

chlorotic). 



No. 205 

(plants 

chlorotic). 



No. 207 

(plants 

healthy). 



No. 208 

(plants 

healthy). 



Insoluble matter 

Potash (K 2 0) 

Lime (CaO) 

Magnesia (MgO) 

Ferric and aluminic oxids (Fe2C>3 and AI5O3) 

Phosphorus pentoxid (P2O6) 

Volatile matter 

Total 

Nitrogen (N) 

Moisture 

Carbon dioxid (CO2) 

Calcium carbonate (CaC03) 

Reaction to litmus 



Per cent. 

86.60 

.20 

1.05 

Trace. 

6.23 

.04 

5.60 



Per cent. 

80.87 

.11 

.98 

Trace. 

10.23 

.05 

7.33 



Per cent. 

88.74 

.20 

.54 

Trace. 

6.92 

.06 

4.71 



Per cent. 

77.14 

.12 

Trace. 

.27 

13. S4 

.05 

8.83 



99.72 



99.57 



100.17 



100.25 



.12 
1.30 

.58 

1.32 

Alkaline. 



.14 
2.38 

.63 
1.46 

Alkaline. 



.13 
.97 

Trace. 

Trace. 
Acid. 



.19 

3.15 

.00 

.00 

Acid. 



Mr. Coll y Cuchi, at kilometer 5, has a small patch of about 200 
chlorotic plants. No. 299 was taken from such a patch and No. 296 
from an area of healthy plants about 5 yards distant. The field 
there being higher than the road the plants are not exposed to drain- 
age from its surface. 

In Mr. Hubbard's plantation, at kilometer 4, there are about 400 
white plants in a hollow below the road. No. 294 is the soil from 
this patch and No. 297 is a sample taken from a patch of healthy 
green plants 10 }^ards distant. 

Mr. Gillies's plantation, at kilometer 3, has about one-tenth acre 
of strongly chlorotic plants in a hollow below the road. Previous 
to planting powdered rock from the road had been thrown on this 
spot. No. 295 is the soil from this bleached spot and No. 298 is 
from a healthy patch of plants 6 yards distant. While in some of 
these cases the plants were exposed to water from the road, in no 
case were the plants suffering from poor drainage. 

Analyses of pineapple soils. 



Soil constituents and reaction. 


No. 299 

(plants 

chlorotic). 


No. 296 

(plants 

healthy). 


No. 294 

(plants 

chlorotic). 


No. 297 

(plants 

healthy). 


No. 295 

(plants 

chlorotic). 


No. 298 

(plants 

healthy). 




Per cent. 

76.70 

.04 

4.18 

.05 

8.55 

.04 

9.98 


Per cent. 

84.47 

.08 

.29 

Trace. 

' 8.25 
.05 
7.01 


Per cent. 

75.43 

.00 

7.55 

.14 

5.39 

.05 

11.15 


Per cent. 

91.56 

.09 

.25 

Trace. 

4.16 

.01 

4.03 


Per cent. 

80.04 

.08 

2.83 

.10 

8.45 

.04 

9.16 


Per cent. 

77.62 


Potash (K 2 0) 


.05 


Lime (CaO) 


.37 




.13 


Ferric and aluminic oxids 
(Fe 2 3 and AI2O3) 


11.60 


Phosphorus pentoxid (P2O5). . 


.05 

9.73 






Total 


99.54 


100.15 


99.77 


100. 10 


100.70 


99.55 








.15 

3.35 

2.73 

6.21 

Alkaline. 


.16 

5.15 

.00 

.00 

Neutral. 


.15 

3.60 

4.70 

10.70 

Alkaline. 


.11 

2.48 

.00 

.00 

Alkaline. 


.14 

4.13 

1.61 

3.66 

Alkaline. 


.20 




9.02 




.00 


Calcium carbonate (CaCOs) - - - 


.00 

Neutral. 







[Bull. 11] 



17 

It can be seen that all the above soils on which chlorotic plants 
were growing are calcareous or rendered so by the drainage water, 
while none of the good soils contain carbonate of lime. 



SOIL SURVEY X. 

Samples were also taken from fields where pineapples were grow- 
ing well on soils which had the same physical character as those pro- 
ducing the chlorotic plants. No chlorotic plants were observed in 
these fields or in the immediate vicinity. Nos. 175 and 176 are sam- 
ples from Campo Alegre, 177 from Manati, 179 and 180 from Rio 
Piedras. 

Analyses of pineapple soils (plants healthy). 



Soil constituents and reactions. 



Insoluble matter 

Potash (K 2 0) 

Lime (CaO > 

Magnesia (MgO) 

Ferric and aluminic oxids (Fe°03 and 

AI2O3) 

Phosphorus pentoxid (P2O5) 

Volatile matter 

Total 

Nitrogen (N) 

Moisture 

Carbon dioxid (CO2) 

(a cium carbonate (CaC0 3 ) 

Reaction to litmus 



No. 175. 



No. 177. 



No. 179. 



Per cent. 

89.78 

.04 

.14 

Trace. 

5.93 

.04 
3.93 



99.86 



Per cent. 

95.04 

.09 

.17 

Trace. 

1.76 

.03 

2.86 



99.95 



.09 

3.34 

.00 

.00 

Acid. 



.05 
3.15 

.00 

.00 

Acid. 



Per cent. 

89.99 

.06 

Trace. 

Trace. 

5.08 

.04 

4.50 



No. 180. 



Per cent. 

96.25 

.04 

Trace. 

Trace. 

.70 

.04 

2.92 



.11 


.09 


1.51 


.59 


.00 


.00 


.00 


.00 


icid. 


Acid. 



No. 176. 



Per cent. 

97. 12 

.03 

.15> 

Trace. 

1.88 
.03 
1.30- 



100.51 



.09 
.50 
.00 
.00 
Acid. 



It will be seen that these good soils are also without calcium 
carbonate. 

The results of the soil surveys are as follows : 

Of the 43 samples of soil analyzed, 22 were taken from areas where 
the pineapples were chlorotic and 21 from areas where they were 
healthy. 

The good soils contain, on an average, 0.11 per cent potash (K 2 0) r 
0.07 per cent phosphoric acid (P 2 5 ), and 0.14 per cent nitrogen (N). 
The bad soils average 0.12 per cent potash (K 2 0), 0.10 per cent phos- 
phoric acid (P 2 5 ), and 0.17 per cent nitrogen (N). Thus the soils 
producing chlorotic plants average higher in nutrients than the soils 
producing healthy plants. 

The chief difference between the soils producing chlorotic and 
healthy plants lies in the content of calcium carbonate (CaCO^. 
The bad 3oils contain from 1.86 to 79.76 per cent of calcium carbo- 
nate (CaCOg). 1 All the good soils contain less than 1.15 per cent 
CaC0 3 and most of them no lime in the form of carbonate. 

1 Nos. 204 and 205 are excepted as here the plants were exposed to the action of a greater amount of lime 
than appears in the soil analyses. 

412°— Bull. 11—11 3 



18 

From an average of the results and from the rather striking nature 
of the evidence in particular cases there seems no doubt but that the 
chlorosis of the pineapple plants is due to the high content of calcium 
carbonate in the soil. 

PINEAPPLE SOILS OF OTHER COUNTRIES. 

No analyses of Cuban pineapple soils are available, but from a 
statement by Prof. F. S. Earle, at one time director of the experiment 
station at Santiago de las Vegas, it appears that pineapple plantings 
on the calcareous soils of Cuba have been unsuccessful. 1 

J. C. Brunnich, chemist of the experiment station of Queensland, 
in a personal communication, reports a disease of the pineapple there, 
induced by poor drainage, but says: "We have no experience of 
pines grown on a strongly calcareous soil." 

The Hawaiian pineapple soils reported by W. P. Kelley 2 average 
about 0.50 per cent of CaO, most of them being acid in reaction, and, 
so far as reported, none of them being calcareous. Certain soils in 
Hawaii were found unfavorable for pineapples due to the Irigh con- 
tent of soluble manganese. This is interesting in illustrating the 
sensitiveness of the pineapple to the chemical character of the soil. 

From numerous analyses by Miller and Hume it appears that the 
good pineapple soils of Florida mainland contain no carbonate of 
lime. 3 The type of soil winch produces the best pineapples there 
contains less than 0.20 per cent of CaO and about 99 per cent of 
insoluble matter. Webber reports that "many plantations have 
been put out on shell land but have uniformly failed." 4 As sea 
shells are composed of calcium carbonate, such soils would be cal- 
careous. 

In the cultivation of pineapples in the Florida Keys, however, we 
have an apparent exception to the proposition that pineapples will 
not grow well on a calcareous soil. Rolfs describes conditions there 
as follows: 

These are islands near the coast of southern Florida. * * * They have a coral- 
line foundation, making a rather porous substratum. * * * In many cases soil, 
jn the ordinary sense, can not be said to exist. In some instances the pineapple 
planter is obliged to choose the spot that has enough decayed vegetable matter to hold 
the plant in place on the coralline rock. The greater part, or nearly all, of the plant 
food is located in the email quantity of decaying vegetable matter; consequently it 
is soon exhausted. 5 

1 Prof. Earle, in a personal communication, states: " The commercial pineapple fields of Cuba are prac- 
tically all on the 'red lands.' These soils always overlie coral rock and are probably derived from it, but 
they carry very little lime, the carbonate of lime seeming to have practically all leached out. These 
soils though stiff and heavy are very permeable and the water passes down through them readily. Pine- 
apples also thrive on certain sandy lands, but they do not do well on heavy black lands. These usually 
carry a considerable percentage of lime, and they are often underlain by 'coco,' a soft material that is 
largely carbonate of lime. Fields planted on these lands produce inferior fruit and usually soon die." 

» Hawaii Sta. Rpt. 1909, p. 58. 

» Florida Sta. Bui. 68. 

«U. S. Dept. Agr. Yearbook 1895, p. 273. 

«U. S. Dept. Agr., Farmers' Bui. 140, p. 14. 
[Bull. 11] 



19 



Miller and Hume 1 report : 

It is the custom to use no fertilizers on the Keys where this kind of soil is found 
and the land becomes exhausted after yielding three or four crops of pineapples. 
At the end of this time the soil is completely worn out, and little more than the bare 
rock remaining it is abandoned. 

The analysis of such a soil shows nearly 5 per cent of lime, 0.30 per 
cent of potash, 0.95 per cent of phosphorus pentoxid, 24.55 per cent 
of humus, and 2.65 per cent of nitrogen. Although this contains a 
high percentage of calcium it is probable, by comparing it with the 
following analyses, that none of this lime was present as carbonate. 

To investigate this matter further, samples of soil were secured 
from two of the Keys through the kindness of the planters. The 
samples received are hardly soils in the strict sense of the word ; they 
are composed exclusively of leaf mold, undecomposed leaves, and 
coral particles. Samples Nos. 209 and 210 were received from Mr. 
T. J. Johnson, of Planter, Fla., and Nos. 214 and 219 from Mr. Edward 
Gottfried, of Key Largo, Fla. No. 219 is a virgin soil and No. 214 is 
from a pineapple field which is now abandoned. 

Analyses of pineapple sails from Florida Keys (plants healthy). 



Soil constituents and reaction. 



No. 209. 



No. 210. 



No. 214. 



No. 219. 



Insoluble matter 

Potash ( K 2 ) 

Lime (CaO) 

Magnesia (MgO) 

Ferric and aluminic oxids (Fe203Al 2 3 ) 

Phosphorus pentoxid ( P2O5) 

Volatile matter 

Total 

Nitrogen (N) 

Moisture 

Carbon dioxid (CO2) 

Calcium carbonate (CaC0 3 ) 

Reaction to litmus 



Per cent. 

3.10 

.23 

21.13 

.56 

1.97 

.40 

71.83 



Per cent. 

6.62 

.29 

20.34 

.69 

5.29 

.30 

66.92 



Per cent. 

3.15 

.19 

17.01 

.17 

2.44 

.25 

76.99 



Per cent. 

2.54 

.18 

10.96 

Trace. 

3.11 

.22 

83.20 



99. 22 



100. 45 



100.00 



100. 21 



1.89 
19.84 
11 05 

25. 14 
Alkaline. 



1.97 
20.05 

9.18 

20.88 

Alkaline. 



2.41 
13.60 
7.59 

17.27 
Alkaline. 



2.61 

19.59 

1.90 

4.32 

Alkaline. 



It will be seen that these "soils" are remarkable for their great 
content of organic matter (as is shown by the high percentages of 
volatile matter and nitrogen) and for their richness in plant food, 
which must be present in a form that is quickly available to the plants. 
The content of lime is high, and while a large part is combined with 
the humus there is still a high percentage of calcium carbonate. It 
is then evident that pineapples will stand a large amount of calcium 
carbonate in the medium in which they grow providing a very large 
amount of organic matter and humus is also present. 

The soil surveys of Porto Rico and the information obtainable from 
Cuba, Hawaii, Queensland, and the Florida mainland, concur in 
showing many cases of the failure of pineapples on calcareous soils 



1 Loc. cit. 



[Bull. 11] 



20 

and no instances of healthy plantings on this soil type. The expe- 
rience of planters on the Florida Keys shows clearly that pineapples 
will grow in a calcareous soil providing it contains a veiy large amount 
of humus. This exception will be considered further on. 

POT EXPERIMENTS WITH DIFFERENT TYPES OF SOIL. 

The soil surveys having shown the calcareous nature of the Porto 
Rico soils unsuited for pineapples, it was desirable to see whether soils 
growing healthy plants would be rendered incapable of producing 
normal plants by the addition of calcium carbonate. For this pur- 
pose a series of pot experiments were carried out. 

Previous to this, however, certain preliminary experiments were 
made to show whether or not the trouble was to be attributed to the 
character of the soil, and also to explain certain apparent exceptions 
that occurred in the field. These experiments are here given in brief. 

On Mr. Noble's plantation (see p. 8) some isolated patches of green 
plants were observed in the midst of chlorotic areas. It was desira- 
ble to see whether these patches of plants remained green due to 
differences in the soil or to individual variations in the plants them- 
selves. Soil from such a patch of green plants together with the 
plants themselves were shipped to the station, also the soil and plants 
from a chlorotic area. The soil from the green plants is No. 102, 
that from the chlorotic plants is No. 101 (see p. 10). These soils 
were placed in pots holding 8 pounds of moisture-free soil and were 
fertilized abundantly from time to time. Five chlorotic plants were 
placed in soil No. 101 and 5 in No. 102. Five of the green plants 
were placed in soil No. 101 and 5 in No. 102. Ten chlorotic plants 
were placed in a good garden soil free from calcium carbonate. The 
green plants in both soils 101 and 102 remained green for some time, 
but as their growth increased they later became chlorotic. The 
chlorosis appeared as rapidly in soil 101 as in soil 102. All the 
chlorotic plants placed in soils 101 and 102 remained chlorotic and 
grew but little. The chlorotic plants placed in the garden soil soon 
recovered their green color and made a good growth. Half of these 
recovered plants were then again returned to soils 101 and 102 and 
here they again became chlorotic and growth ceased. 

It is apparent from this that soils 101 and 102 are practically the 
same, and that the occurrence of green plants on one of them was due 
to the fact that the slips planted there were of greater vigor than the 
others. Field results confirmed this view, as later the isolated green 
plants on this plantation lost their color. The fact that chlorotic 
plants recovered in the good garden soil and again became chlorotic 
on returning to the original soil shows that the chlorosis was proba- 
bly induced by the soil and is not an organic disease. 

The following experiments and the success of the transplanted 
plants on Mr. Noble's plantation (see p. 8) confirm this. 

[Bull. 11] 



21 

Soil and chlorotic plants were secured from Lnquillo (see p. 9). 
The soil was placed in pots and well fertilized. Five chlorotic plants 
were placed in the original soil; these remained chlorotic with very- 
little growth. Five chlorotic plants placed in a river sand devoid of 
calcium carbonate became green and made a good growth. Five 
healthy slips placed in the Luquillo soil grew well for a time and then 
became chlorotic. 

Chlorotic plants were also secured from the plantation of Messrs. 
De Sola and Wolff (see p. 15). These on being placed in pots of the 
river sand became green and grew normally. 

These three preliminary experiments showed plainly that the chlo- 
rosis is induced by an unsuitable soil condition, probably the presence 
of too much carbonate of lime. 

Sandy soil was then secured from a plantation near Mayaguez 
where pineapples were growing well. The soil is No. 232 (see p. 15). 
Carbonate of lime in the form of ground sea shells was added to this 
soil in such amounts that different pots contained 5, 10, 13, and 17 
per cent of calcium carbonate. Five equal Red Spanish slips were 
planted. The check plant in the soil containing no calcium carbonate 
remained green throughout the experiment, while all the other plants 
became chlorotic, the chlorosis appearing first and being most intense 
in those pots containing the greatest amount of lime. 

Experiments were then made on a larger scale to see if the addition 
of calcium carbonate to a soil would cause it to produce chlorotic 
plants. The details of the experiments follow. 

The plants were grown in pots that contained 40 pounds of moisture- 
free soil. These were exposed in the open on tables that were pro- 
tected from ants and mealy bugs. Water was supplied only a few 
times in the course of the experiment, as the rainfall was sufficient 
to maintain a good supply of moisture during the period. The size 
of the pots and the frequent rains prevented any appreciable varia- 
tions occurring in the water content of individual pots due to dif- 
ferences in the transpiration of the plants. In each pot only one 
plant was grown, so that practically as much soil was at the disposal 
of the plant as under field conditions. The experiments were run in 
series of five, that is, in every case there were five pots receiving the 
same treatment. 

The pots were planted with suckers obtained from healthy plants 
grown on the station. Previous to planting, all slips were fumigated 
with hydrocyanic-acid gas to kill any mealy bugs or other pests. 
Five different sizes of slips, varying from 6 to 14 inches in length, 
were used in each lot of five pots, but the slips in each lot of five were 
equal to those of every other lot of five. Slips of different sizes were 
used for the purpose of seeing whether the appearance of the chlorosis 
was affected by the initial vigor of the slip. 

[Bull. 11] 



22 

Experiments were made with three different types of soil — with a 
loose river sand, with a loamy clay, and with a soil composed cliiefly 
of organic matter. This latter soil was prepared artificially by 
mixing a small amount of sandy soil with well-weathered manure. 

The analyses of the soils are as follows: 

Analyses of soils used in pot experiments. 



Soil constituents and reaction. 



Insoluble matter 

Potash ( K 2 ) 

Lime ( CaO) 

Magnesia (MgO) 

Ferric and aluminic oxids (Fe20 3 and A1 2 3 ) 

Phosphorus pentoxid ( P2O5) 

Volatile matter 

Total 

Nitrogen (N) 

Moisture 

Carbon dioxid (C0 2 ) 

Calcium carbonate (CaC0 3 ) 

Reaction to litmus 



No. 213 
(sandysoil). 



Per cent. 

67. 38 

.01 

1.23 

2. 21 

2L90 

.08 

6.59 



99. 40 



.05 

7.38 

None. 

None. 

Neutral. 



No. 18 

(clay loam 

soil). 



Per cent. 

60.38 

.30 

.85 

3.58 

23.91 

.20 

11.55 



100.77 



.19 

11.46 

None. 

None. 

Neutral. 



No. 222 

(soil rich 

in humus). 



Per cent. 

47.49 

.48 

3.82 

2.92 

11.49 

.55 

33.25 



100. 00 



.69 

5.83 

None. 

None. 
Acid. 



Lime was added to these soils in the form of carbonate. The 
limestone used was of coralline origin and occurs naturally in a finely 
disintegrated state. The use of this material made it possible to 
imitate closely natural conditions, as tliis limestone forms the subsoil 
of many fields and is of the same origin as much of the calcium car- 
bonate occurring in Porto Kico calcareous soils. 1 In all experiments 
except No. IV such a limestone, obtained from Tallaboa, was used. 
The analysis is given below under No. 216. In experiment IV a 
limestone of the same kind but containing more magnesium was used, 
the analysis of which is given under 211. 

Analyses of limestone used in pot experiments. 



Soil constituents. 



No. 211 

(used in 

experiment 

IV). 




Silica and sand (Si0 2 ) 

Iron and alumina (Fe20 3 and A1>0 3 ) 

Lime (CaO) 

Magnesium (MgO) 

Loss on ignition 

Total 



Per cent. 

0.20 

.68 

49.82 

4.86 

44.32 



99. 88 



The pots were all lertiJized alike from time to time. The fertiliza- 
tion was rather more liberal than necessary in order to show beyond 
doubt that the chlorosis was not induced by lack of nitrogen, phos- 
phorus, or potash. Tankage, sodium nitrate, sulphate of potash, 



i The effectiveness in the soil of calcium and magnesium carbonate from different sources is compared 
by D. Meyer (Landw. Jahrb., 33 (1904), p. 371). 

[Bull. 11] 



Bui. 1 1, Porto Rico Agr, Expt. Station. 



Plate II. 




Fig. 1.— Effect of Carbonate of Lime on the Growth of Pineapples. 




Fig. 2.— Effect of Ferrous Sulphate on Chlorotic Pineapple Plants. 



23 



and acid phosphate were mixed with the soil in such quantities that 
during the period of growth each pot received 4.1 grams of nitrogen, 
3.1 grams of phosphoric acid, and 6.7 grams of potash. The ferti- 
lizer was given in different applications to prevent too great a quan- 
tity of soluble salts being present at one time and also because there 
was probably a certain loss by leaching caused by the heavy showers. 

The plants were grown for a period of 10 months, and during tins 
time the check plants made a growth equal or superior to that of 
plants in the field. A record was kept of each plant in regard to the 
appearance of chlorosis. After 10 months' growth the plants were 
cut and weighed in the green condition. 

The principal purpose of the experiments was qualitative — to 
observe the effect of calcium carbonate in producing a chlorotic 
appearance of the plants, but the comparative weights show in a 
general way the condition of the plants and give an idea of its effect 
on the growth. Accurate quantitative data of small differences in 
growth can not be obtained in pot experiments with pineapples, as 
it is impracticable to grow enough individuals to secure a fair average. 
. In experiment I the sandy soil No. 213 was used and the limestone 
No. 216. The five check pots contained no lime; the other lots of 
five pots each contained, respectively, 10, 20, 30, 40, and 50 per cent 
of calcium carbonate. Suckers of Red Spanish pineapples were 
planted. In the next table are given the appearance of the plants at 
four, six, and nine months, and the average green weight. 

The object of the experiment was to see whether the addition of 
calcium carbonate to a good sandy soil would cause it to produce 
chlorotic plants. By consulting the table it will be seen that all the 
check plants made a good growth and remained dark green during 
the 10 months; that all the plants in pots containing carbonate of 
lime showed varying degrees of chlorosis and a great depression in 
growth; that the chlorosis was most intense in the pots containing 
the greatest amount of lime. (PI. II, fig. 1.) 

Results of experiment in which calcium carbonate was added to sandy soil. 



Amount of 
CaC0 3 in soil. 


Appearance of plants during growth. 


Average 

green 

weight of 5 

plants at 

end of 10 
months. 


Check 




Grams. 
1,022 


10 percent 

20 percent 

30 per cent 

40 per cent 

50 per cent 


Color of all 5 plants lighter than check at fourth month; at sixth month J 

plants slightly chlorotic; at ninth month all slightly chlorotic. 
At fourth month 2 plants slightly chlorotic, others light green; at sixth 

month all slightly chlorotic; at ninth month all 5 chlorotic. 
At fourth month all 5 plants light green; at sixth month 4 plants chlorotic; 

at ninth month all chlorotic and 3 very strongly. 
At fourth month 4 plants slightly chlorotic and 1 plant light green; at sixth 

month all chlorotic; at ninth month all 5 strongly chlorotic. 
At fourth month all slightly chlorotic; at sixth month all chlorotic; at ninth 

month all 5 strongly chlorotic. 


596 
584 
623 
549 
400 



[Bull. 11] 



24 



Experiment II is the same as experiment I throughout, except 
that the loamy clay soil No. 18 was used instead of the sandy soil. 
The results are given in the table below. 

The object of this experiment was to see whether the chlorosis 
would be as intense in a calcareous clay as in a sandy soil. The 
results show that check plants had a good color throughout the 
experiment and made a fair growth, though not equal to that of the 
check plants in experiment I; that 10 per cent of calcium carbonate 
did not produce as intense a chlorosis as the same amount of lime in 
a sandy soil; that 20 to 50 per cent of calcium carbonate caused as 
intense a chlorosis in the clay soil as in the sand, though the plants 
made a greater growth. 

Results of experiment in which calcium carbonate was added to loamy soil. 



Amount of 
CaCOj in soil. 


Appearance of plants during growth. 


Average 
green 
weight of 5 
plants at 
end of 10 
months. 


Check. . . 




Grams. 

781 


10 percent. . 
20 percent 

40 per cent 

SO per cent 


Color of 2 plants lighter than check at fourth month; at sixth month 2 plants 

slightly chlorotic; at ninth month 1 plant chlorotic, 4 plants inferior to 

check in color. 
Three plants showed symptons of chlorosis at fourth month; at sixth month 

3 plants chlorotic, 1 slightly affected; at ninth month 3 plants chlorotic, 

2 slightly affected. 
Color of 5 plants lighter than check at fourth month; at sixth month 3 chlorotic 

at center, 1 slightly chlorotic: at ninth month all 5 plants chlorotic. 
At fourth month 1 plant strongly chlorotic, 2 plants color equal to check, 2 

plants color lighter than check; at sixth month all 5 plants chlorotic; at 

ninth month all plants strongly chlorotic. 
At fourth month 1 plant slightly chlorotic, 4 plants color lighter than check; 

at sixth month all 5 plants chlorotic; at ninth month all plants strongly 

chlorotic. 


622 

685 

650 
471 

534 



Experiment III is the same as experiment I throughout, except 
that the soil rich in humus (No. 222) was used. The results are 
given in the table following. 

The object of this experiment was to see whether the addition of 
calcium carbonate to a soil exceptionally rich in organic matter would 
cause it to produce chlorotic plants. Briefly the results were: The 
check plants maintained a good color and made an exceptional growth; 
the plants in the pots with 10 to 30 per cent of calcium carbonate were 
practically equal to the checks in color and growth ; three plants in the 
pots with 40 per cent calcium carbonate showed chlorosis at the sixth 
month but recovered later, the growth being about equal to the checks; 
the five plants in the pots with 50 per cent calcium carbonate were 
slightly chlorotic at six months but all except one recovered their 
green color later. The results of this experiment are in harmony with 
the conditions obtaining in the Florida- Keys. They show that the 
tendency of calcium carbonate to cause chlorosis is counteracted by 

[Bull. 11] 



25 

a large amount of organic matter, but that when the proportion of 
organic matter to calcium carbonate falls below a certain point chlo- 
rosis is produced in spite of the large amount of humus. 

Results of experiment in which calcium carbonate was added to a soil rich in humus. 



Amount of 
CaCOs in soil. 



Appearance of plants during growth. 



Average 
green 
weight of 5 
plants at 
end of 10 
months. 



Check 

10 per cent . 
20 per cent . 
30 percent. 
40 per cent . 



50 per cent . 



All plants dark green throughout the experiment 

All plants equal to check in color throughout the experiment 

do 

do 

At fourth month color of all plants equal to check; at sixth month 2 plants 
chlorotic and 1 slightly chlorotic; at ninth month 1 plant slightly chlorotic, 
others equal to check. 

At fourth month color of all plants equal to check at sixth month all plants 
strongly chlorotic; at ninth month 1 plant chlorotic, 4 very slightly chlo- 
rotic. 



Grams. 
1,137 
812 
1,048 
1,117 
1,006 



Experiment IV is the same as experiment I throughout, except 
that the magnesia limestone (No. 211) was used, instead of No. 216. 
As but 75 pounds of this limestone was available, only the effect of 
soils containing 10 and 30 per cent of the combined carbonates (of 
lime and magnesia) was tried. The results are given in the table 
below. 

The object of this experiment was to see if increasing the available 
magnesium in the soil would lessen the chlorosis. The results were: 
The check plants maintained a good green growth; the plants in all 
the pots with the magnesium limestone became chlorotic; the chlo- 
rosis was fully as intense as in the parallel experiment with the lime- 
stone low in magnesia (experiment I). It is apparent that increasing 
the ratio of magnesium carbonate to calcium carbonate from 1:51 to 
1 : 9 has no beneficial effect in diminishing the chlorosis or increasing 
the growth of the plants. 

Results of experiment in which limestone containing 10 per cent of magnesium carbonate 

was added to sandy soil. 



Amount of 
combined car- 
bonates (lime 
and magnesia) 
in soil. 


Appearance of plants during growth. 


Average 
green 
weight of 5 
plants at 
end of 10 
months. 


Check 




Grams. 

653 


10 per cent 

30 per cent 


At fourth month color of all plants poorer than the check; at sixth mont b 1 

plant dead, 2 plants slightly chlorotic; at ninth month all plants slightly 

chlorotic. 
At fourth month 1 plant chlorotic, 4 plants color inferior to check; at sixth 

month 1 plant strongly chlorotic, 4 plants very slightly chlorotic; at ninth 

month all intensely chlorotic. 


508 
358 



[Bull. 11J 



26 

EXPERIMENTS WITH PLANTS GROWN IN SMALL FIELD PLATS. 

Ill addition to the pot cultures an experiment was made under natural 
conditions in the following manner: Four holes, 20 by 10 feet and 2 feet 
deep, were dug and filled with prepared soil. The plats were sur- 
rounded by a ditch and separated from each other by 3 feet of clay 
soil. One plat was made up of a loamy soil containing no carbonate 
of lime. The other three plats contained respectively 10 per cent, 
25 per cent, and 50 per cent of calcium carbonate. The limestone 
used was No. 216 and was very thoroughly mixed with the soil. In 
each plat 16 Red Spanish slips were planted. The plants were here 
growing under perfectly natural conditions of moisture, temperature, 
and root space. 

All the plants in the check plat, with no carbonate of lime, made a 
good green growth throughout the experiment. The plants in the 
plat with 10 per cent of calcium carbonate at the end of five months 
were distinctly inferior in color, being a very light green. At the 
end of seven months 11 plants, which had made a fair growth, were 
strongly chlorotic; the remaining 5 plants, which had grown but 
little, were only slightly chlorotic. At the tenth' month they were 
all slightly chlorotic. The plants in the third plat, with 25 per cent 
of calcium carbonate, were slightly chlorotic at the fifth month. At 
the seventh month the 12 plants which had made a fair growth were 
very strongly chlorotic, being creamy white in color, while the 
remaining 4 plants, which had made little growth, were slightly 
chlorotic. At the tenth month all plants were strongly chlorotic. 
The plants in the fourth plat, with 50 per cent of calcium carbonate, 
were slightly chlorotic at the fifth month, and at the seventh month 
the 7 largest plants were creamy white, the remaining 9 plants of 
little growth were plainly though not intensely chlorotic. At the 
tenth month all were intensely chlorotic. At the end of 10 months 
the plants were cut and the average green weight of the plants was 
as follows : 

Average xoeight of plants. 

Grams. 

( 'heck plat, no calcium carbonate 568 

Plat with 10 per cent calcium carbonate 423 

Plat with 25 per cent calcium carbonate 437 

Plat with 50 per cent calcium carbonate 374 

The results of the experiments with plants grown in pots and in 
small field plats were as follows: 

Plants grown on sandy and loamy soils to which natural carbonate 
of lime was added became chlorotic. Plants grown in a soil which 
was practically pure organic matter showed no chlorosis until the 
percentage of carbonate of lime reached 50 per cent. 

[Bull. 11] 



27 

Limestone containing 10 per cent of magnesium carbonate pro- 
duced as intense a chlorosis as a limestone containing 1 per cent of 
magnesium carbonate. 

The plants usually showed a slight chlorosis four or five months 
after planting and at the ninth month were strongly chlorotic. In 
all the experiments it was observed that the chlorosis was somewhat 
dependent on the growth. Plants which grew slowly at first did not 
become chlorotic as quickly as those which made a quick start. 
Also, the plants originating from small slips became chlorotic much 
sooner than those originating from large ones. Plants coming from 
very small but vigorous slips, which made a quick growth at the 
start, were the type that showed the chlorosis first and most intensely. 

From these observations it would appear that the chlorosis was 
dependent either on the exhaustion of a nutrient stored in the slip, 
which the plant was later unable to obtain from the calcareous soil, 
or on the absorption of an injurious amount of an element from the 
soil. 

CONCLUSIONS FROM SOIL INVESTIGATIONS. 

The results of the culture experiments confirm the conclusions 
arrived at by the soil survey. It is evident that the chlorosis of the 
pineapples observed on certain plantations is caused by an excessive 
amount of calcium carbonate in the soil. Experiments show that 
additions of calcium carbonate to soils that produce healthy plants 
cause these soils to produce chlorotic plants. Soils unusually rich 
in humus and organic matter require a large amount of carbonate of 
lime to cause them to produce chlorotic plants. Soils of this latter 
type do not exist in Porto Rico to our present knowledge. 

No attempt was made to find by pot experiments the smallest 
amount of calcium carbonate in. soils that would cause this chlorosis, 
since the analyses of the different pineapple soils found actually pro- 
ducing chlorotic plants show this more accurately than could be 
determined by pot experiments. In reviewing the analyses it will be 
seen that the highest content of calcium carbonate found in any soil 
producing healthy plants was 1.15 per cent. The lowest content of 
calcium carbonate found in any of the soils producing chlorotic 
plants was about 2 per cent. This was a loose sandy soil. Thus, for 
sandy soils, a content of 2 per cent of calcium carbonate renders them 
unfit for pineapples. Possibly a sandy soil containing 2 per cent of 
carbonate of lime and at the same time a good content of humus 
might produce healthy plants, but in general it can be safely said that 
sandy soils containing 2 per cent or more of calcium carbonate are 
unfitted for pineapples. The danger limit for loamy soils may be a 
trifle higher. The only loamy soil which was found producing 
chlorotic plants contained 4.62 per cent of calcium carbonate. 

[Bull. 11] 



28 

Different varieties of pineapples may vaiy somewhat in their 
sensitiveness to lime, but, as the Cabezona variety has been found 
showing chlorosis in asoil containing 3.30 percent of calcium carbonate, 
this variety can not be considered more resistant than the Red Spanish. 
In only one case were the native varieties Caraquefia and Pan de 
Azucar found growing in a calcareous soil. This soil contained 21.77 
per cent of calcium carbonate and the plants were strongly chlorotic. 
At present the Cabezona and Red Spanish are the only varieties of 
pineapples grown commercially in Porto Rico. It is possible that 
the Smooth Cayenne and some other varieties which have poorer 
shipping qualities might prove more resistant. 

From the foregoing it appears that pineapples are almost as sensi- 
tive to calcium carbonate as lupines, which will not grow in a soil 
containing 2 per cent of calcium carbonate. 

Since calcareous soils containing a large amount of humus do not 
produce chlorotic plants, it might be thought that by raising the humus 
content of these soils they could be made to grow pineapples. In 
fact, applications of barnyard manure were found to produce some 
improvement in the plants. For most of these calcareous soils, 
however, it is impracticable to raise the humus content sufficiently 
high to render them suitable for pineapples. Probably heavy appli- 
cations of barnyard manure or other organic matter to soils contain- 
ing but 2 per cent of calcium carbonate would much improve the 
condition of the plants. 

In the following pages is described another means of overcoming 
the disturbances in the plant associated with the chlorosis, and of 
restoring the normal green (chlorophyll) to the leaves. Nevertheless, 
it is improbable that this treatment will be commercially successful. 
In the present condition of the pineapple industry in Porto Rico, 
where there are still large unplanted areas suitable for pineapples, it is 
not advisable to plant on soils which require extra, and fairly expen- 
sive, treatment to produce a crop. It is better to abandon the plant- 
ings of pineapples on these calcareous soils and put in crops which 
are adapted to this type of soil. 

The calcareous sands near the sea are well adapted to coconuts. 
On the sandy soils which do not contain an excessive amount of car- 
bonate of lime, gandules and citrus trees are found growing well. 
Tobacco does well on the calcareous soils which are not too near the 
sea. It is advisable to plant these calcareous soils to one of the above 
crops rather than to pineapples which will require extra treatment 
to yield a crop. 

[Bull. 11] 



29 

INVESTIGATIONS OF THE CHLOROSIS. 

PREVIOUS WORK ON LIME-INDTJCED CHLOROSIS. 

Although it has never before been shown that pineapples are 
intolerant of calcium carbonate and that chlorosis is induced in this 
plant by the excessive amount of lime, If has been observed that many 
other species of plants growing on calcareous soils show chlorosis. 
The amount of lime that plants will tolerate varies greatly with the 
different species and also with the different varieties of the same 
species. The chlorosis of grapevines on certain marly soils of France 
and Germany is probably the best known example of lime-induced 
chlorosis. Some American phyloxera-resistant stocks show chlorosis 
on soils containing as little as 5 per cent of carbonate of lime; other 
American stocks are much more resistant, while certain native French 
stocks and hybrids show no chlorosis on soils containing 50 to 70 per 
cent of lime carbonate. 1 

Yellow and blue lupines and seradella are very sensitive to lime, 
only tolerating about 2 per cent of calcium carbonate in the soil, and 
their growth is greatly depressed in soils containing as little as 1 per 
cent. 2 The varieties of lupines, Lupinus mutabilis, L. alius and L. 
nanus, however, are lime-loving plants and resist even 30 per cent of 
lime carbonate. 3 

A chlorosis of pear trees growing on a strongly calcareous soil of the 
Isle of Sainte-Anne is reported by Dauthenay. 4 In Hertfordshire, 
England, an orchard of various fruit trees planted on a soil overlying 
a chalk formation was strongly affected with chlorosis. The surface 
soil contained 13.53 per cent of lime carbonate. Pears, peaches, 
plums, nectarines, apricots, and cherries were among the trees 
affected. 5 Hilgard reports a chlorosis of citrus trees growing on a 
marly subsoil containing 22 to 39 per cent of lime carbonate. 6 

The chlorosis of many ornamental and uncultivated plants growing 
on calcareous soils has also been observed. Sachs 7 reports the 
chlorosis of a large number of plants growing in the garden of the 
Botanical Institute in Wiirzburg. The soil of this garden he de- 
scribes as strongly calcareous. 

Aside from the observations of the chlorosis of plants on calcareous 
soils there is an extensive literature on the adaptability of various 
plants to calcareous soils. 

1 The amount of lime that the different varieties of grapevines will tolerate is given by J. M. Guillon and 
O. Brunaud. Rev. Vit., 20 (1903), p. 535. 

2 Landw. Jahrb., 30 (1901), Sup. 2, p. 61. 

3 J. A. C. Roux. Trait6 des Rapports des Plantes avec le sol et de la Chlorose Yegetale. Montpellier and. 
Paris, 1900, p. 132. 

* II. Dauthenay. Rev. Hort. [Paris], 73 (1901), p. 50. 

5 R. L. Castle. Gard. Chron., 3. ser., 25 (1899), No. 052, p. 405; 26 (1899), No. 653, p. 4. 
« California Sta. Circ. 27. 

7 J. Sachs. Arb. Bot. Inst. Wiirzburg, 3 (1888), p. 433. 
[Bull. 11] 



30 

Hilgard, 1 Hoffmann, 2 Braungart, 3 Roux, 4 and a great many others 
have observed that certain species of plants fail to make a normal 
growth on calcareous soils or refuse to grow at all. On the other 
hand there are certain plants which only reach their fullest develop- 
ment on soils that are rich in calcium carbonate. 

Although it is so well known that certain plants become chlorotic 
when grown on calcareous soils, the way in which the lime acts in 
producing the chlorosis is not well understood. As long ago as 1843 
Eusebe Gris showed that by treatment with ferrous sulphate chlorotic 
plants become green. Much later Sachs 5 treated many chlorotic 
plants successfully with ferrous sulphate. A great deal of work has 
been done in France and Germany on the treatment of chlorotic 
grapevines with ferrous sulphate and other compounds of iron. 6 
These treatments where they have not completely restored the normal 
green to the leaves have markedlv diminished the chlorosis. Hiltner 7 
has restored the green color to chlorotic lupines growing on a strongly 
calcareous soil. 

That the effectiveness of the ferrous sulphate in overcoming the 
chlorosis is due merely to the iron was well shown by Guillon, 8 who 
treated chlorotic grapevines with ferrous sulphate, sulphuric acid, 
sodium sulphate, and with the tannate, malate, and citrate of iron. 
Only the iron compounds were effective. Hiltner 7 in a similar 
manner, confirmed this in his treatment of lupines. 

The opinion of those who have treated successfully the chlorotic 
plants with ferrous sulphate and ferric chlorid is, in general, that 
the chlorosis of the plants is caused by a lack of iron in the plant, the 
plant being unable to take up the necessary amount of iron in cal- 
careous soils. However, comparative analyses made of chlorotic 
and green leaves and wood of the grapevine by Schulze 9 show that 
the healthy plant contains much more potash than the chlorotic plant. 
Mach and Kurmann 10 obtained similar results. Others, therefore, 
including Sorauer 11 and Euler, 12 have the opinion that the chlorosis 
is largely induced by a lack of potash. 

i E. W. migard. Soils. New York, 1906. Proc. Soc. Prom. Agr. Sci., 7 (1886), p. 32; Forsch. Ceb. 
Agr. Phys.,10(1888),p.l85. 

2 H. Hoffmann. Landw. Vers. Stat., 13 (1871), p. 269. 

3 R. Braungart. Jour. Landw., 28 (1880), p. 155. 

* J. A. C Roux. Traits des Rapports des Plantes avec le sol et de la Chlorose V6g6tale. Montpellier and 

Paris, 1900. 

5 Loc. cit. 

s Luedecke. Ztschr. Landw. Ver. Grossherzogthums Hessen, 62 (1892), No. 41, p. 333; 63 (1893), No. 2, p. 9- 
A. Bernard, Prog. Agr. et Vit., 18 (1892), pp. 36-42. J. M. Guillon, Prog. Agr. et Vit., 26 (1896), pp. 606-608. 
A. Menudier, Jour. Agr. Prat., 60 (1896), II, pp. 157, 158. J. Dufour, Ber. Schweiz. Bot. Gesell., 1892, No. 
2, pp. 44-46. 

7 L. Hiltner. Prakt. Bl. Pflanzenbau u. Pflanzenschutz, n. ser., 7 (1909), Nos. 2, 3, 5. 

s J. M. Guillon. Prog. Agr. et Vit., 23 (1895), p. 653. 

9 E. Schulze. Centbl. Agr. Chem., 2 (1872), p. 99. 

io Centbl. Agr. Chem., 1877, p. 58. 

« Paul Sorauer. Handbuch der Pflanzenkrankheiten, Berlin, 1909, 3. ed., vol. 1, p. 310. 

" H. Euler. Grundlagen und Ergebnisse der Pflanzenchemie. Braunschweig, 1909, pt. 3, p. 153. 
[Bull. 11] 



31 



Hollrung 1 is of the opinion that the alkalinity of calcareous soils 
is one of the principal causes of the chlorosis of grapevines, as they 
seem to grow best on slightly acid soils. Molz 2 is of the opinion that 
the chlorosis of grapes is largely caused by the physical condition of 
the soil. 

From the previous work on chlorosis it is then apparent that certain 
plants growing on calcareous soils become cnlorofic, and that treat- 
ment with certain iron salts is more or less effective in ameliorating 
the chlorotic condition. As to just how the carbonate of lime acts in 
causing the chlorosis there is some difference of opinion. 

To ascertain if possible how the lime disturbs the physiology of 
pineapples and induces the chlorosis the following investigations 
were made. 

EFFECT OF SOIL ALKALINITY AND ASSIMILABLE LIME IN 
CAUSING CHLOROSIS. 

Chemically calcareous soils differ chiefly from ordinary soils in 
having an alkaline reaction and in containing a large amount of easily 
assimilable lime. If the mere alkalinity of the calcareous soils were 
the causative feature it would be expected that soils rendered alkaline 
with sodium carbonate would also produce chlorotic plants. If the 
large amount of assimilable lime causes the chlorosis it would be 
expected that soils treated with calcium sulphate would produce 
chlorotic plants. To determine whether the chlorosis is caused 
either by the alkalinity or the large amount of assimilable lime, pot 
experiments were carried out. 

The experiments were carried out after the manner described on 
page 21 except that the pots receiving sodium carbonate were kept 
in the glass house to prevent loss of the alkali by leaching. 

In the experiment with sodium carbonate the soil used was No. 
213. Five check pots received nothing, five received sufficient 
anhydrous sodium carbonate to give the soil a content of 0.01 per cent, 
five received sodium carbonate to 0.05 per cent, and five sodium 
carbonate to 0.10 per cent of the weight of soil. The condition of the 
plants at the end of 10 months is given in the following table: 
Results of experiment in which sodium carbonate was added to sandy soil. 



Content of 
NasCOa in soil. 


Appearance of plants. 


Average 
green 
weight of 5 
plants at 
end of 10 
months. 


Check 




Grams. 

700 


0.01 per cent . . . 
0.05 per cent 
0.10 per cent. . . 




294 


do 


264 




185 







« M. Hollrung. Landw. Jahrb., 37 (1908), pp. 497-616. 

» E. Molz. Centbl. Bakt. [etc.], 2. Abt , 19 (1907), Nos. 13-15, p. 461; 16-18, p. 563; 21-23, p. 715; 24-25, 
p. 788; 20(1907), Nos. 1-3, p. 71; 4-5, p. 126. 

[Bull. 11] 



32 



The results in brief were: The check plants made a good green 
growth; the plants in the pots with sodium carbonate were greatly 
depressed in growth; those in the pots with 0.10 per cent of Na 2 C0 3 
making scarcely any growth; but all plants maintained a good dark 
green color. 

It is, then, evident that it is not alone the soil alkalinity lhat 
causes the chlorosis. While the alkalinity produced by 0.01 per cent 
of Na 2 C0 3 is sufficient to greatly depress the growth of the plant, it 
disturbs the nutrition in a very different manner from CaC0 3 , as it 
apparently has no effect on the formation of chlorophyll. 

In the experiment with calcium sulphate, or gypsum, soil No. 18 
was used. Five check pots received no gypsum, five pots received 
sufficient gypsum to give the soil a content of 5 per cent CaO, five 
gypsum to a content of 10 per cent CaO and five gypsum to a content 
of 15 per cent CaO. The results are given in the following table: 

Results of experiment in which gypsum was added to loamy soil. 



Content of CaS0 4 .2H 2 and CaO in soil. 


Appearance of plants. 


Average 
weight of 
5 plants. 


Check 




Grams. 

004 




do r. * 


482 


5 per cent CaO. 
30.65 per cent CaS0 ( .2H 2 0, equivalent 

to 10 percent CaO. 
45.98 per cent CaSO<.2H 2 0, equivalent 

to 15 per cent CaO. 


do 


452 


Plants poorer color than others throughout the 
experiment, though not chlorotic. 


470 



It appears that wliile the heavy application of gypsum depressed 
the growth, like the sodium carbonate it failed to produce the 
chlorosis. 

Since, then, it is neither the alkalinity alone nor the large amount 
of assimilable lime that induces the chlorosis, it would seem that the 
chlorosis is induced by both these factors working together. These 
factors may act directly on the plant or indirectly, by their effect on 
some of the nutrients contained in the soil. 

TREATMENT OF CHLOROTIC PLANTS WITH IRON AND OTHER 

SALTS. 

A number of experiments were made to overcome the chlorosis. 
Chlorotic plants growing in pots of calcareous soil were treated in 
various ways. Watering with Knop's nutrient solution was inef- 
fective. This was partly to be expected, as heavy applications of 
nitrogen, potash, and phosphoric acid were found unavailing in check- 
ing the chlorosis. Additions of magnesium sulphate to the soil at 
intervals gave no result. If an unfavorable ratio of lime to mag- 
nesium were the cause of the trouble, this treatment should have 
proven beneficial. 

[Bull. 11] 



33 

Treatment with iron salts, however, was signally effective in 
restoring the normal green color to the leaves. At first, 2 per cent 
solutions of ferrous sulphate were added to the soil in which chlorotic 
plants were growing without improving the condition of the plants 
at all. Crystals of ferrous sulphate were then put in the soil, either 
touching the roots or in their immediate vicinity. Three weeks 
after the application the treated plants had improved considerably 
in color, one month later the treated plants were practically a normal 
green and had increased considerably in growth. The untreated 
chlorotic plants which served as checks remained practically white 
and without growth. (PI. II, fig. 2.) 

Chlorotic plants were also treated by brushing the leaves with a 
2 per cent solution of ferrous sulphate, a 2 per cent solution of ferric 
chlorid, and a 2 per cent solution of sulphuric acid. The brushing 
was repeated four times, at intervals of 10 days. The plants treated 
with sulphuric acid showed no improvement, while those treated 
with the iron salts were considerably greener two weeks after the 
first brushing, and three weeks later were of a normal green. The 
facts that sulphuric acid was ineffective and that ferric chlorid and 
ferrous sulphate were equally effective in curing the chlorosis indi- 
cate that the action is to be attributed to the iron alone and not to 
the sulphate radical nor to the acidity of the salts. 

One plant, the leaves of which were almost waxy white, except 
for a few brown spots where decay was starting, was treated by 
dropping a crystal of ferrous sulphate in the heart. The center 
leaves were burnt out by the acidity of the salt, but the other leaves 
became green and a vigorous green shoot was sent out. 

The effectiveness of brushing with iron salts depends upon the 
solution penetrating the epidermis of the leaves. Leaves which were 
burnt by the strength of the solution became green much more 
rapidly than uninjured leaves. Leaves winch were pricked previous 
to the brushing, so that the solution could penetrate readily, became 
green sooner than unpricked leaves. 

While the above treatments were signally effective in restoring the 
normal color and growth to plants, one treatment does not suffice for 
the life of the plant. Three or four months after the restoration of 
the green color, or chlorophyll, the new leaves commence to show 
chlorosis, and the whole plant gradually becomes chlorotic again. 
A renewed treatment with iron is again effective. 

To grow pineapples on strongly calcareous soils would necessitate 
repeatedly spraying the plants with ferrous sulphate, as applications 
of ferrous sulphate to the soil are unavailing. It is possible that on 
calcareous soils, containing from 2 to 5 per cent of calcium carbonate, 
an application of ferrous sulphate to the soil might be efficacious, as 

[Bull. 11] 



34 

with a smaller amount of lime the iron would not be rendered unavail- 
able so quickly. 

It is very doubtful if treatment with iron salts would render pine- 
apple growing on calcareous soils commercially successful, as the 
repeated treatments with iron would be expensive and the crop 
would not be equal to that secured from soils naturally adapted to 
pineapples. 

ASH CONTENT OF GREEN AND CHLOROTIC LEAVES. 

An examination was made of the ash content of green and chlorotic 
leaves. Since the chlorosis is evidently caused by a disturbance in 
the mineral nutrition of the plant, it was thought that the difference 
between the ash content of green and chlorotic leaves ought to make 
evident in what the disturbance consists. As the ash varies con- 
siderably with the age of the plant, only plants of the same age were 
taken for the comparative analyses. 

The analyses were made according to the official methods of the 
Association of Official Agricultural Chemists for plant ashes, with 
two exceptions. As the content of lime in all the ashes far exceeds 
that of phosphoric acid, no addition of calcium acetate was made 
previous to the ignition, which took place over a very low flame. 
Check analyses were run on samples ignited with and without cal- 
cium acetate and it was found that there was no loss of phosphoric 
acid in the ignition without calcium acetate and that the lime could 
be determined more accurately without the acetate addition. The 
determination of potash was made according to the method given by 
Konig 1 ; as for the determination of potash alone in these ashes, this 
method was more accurate. 

The plants from experiments I, II, and III (see pp. 23-25) were 
analyzed at the close of the experiments. As the experiments were 
run in series of five, equal samples of the dried substance of each of 
the five plants were combined to make a composite sample for the 
analysis. The analytical results in the table below are thus an 
average of the five plants grown under like conditions. All the plants 
in this table were 10 months old and the plants in each experiment 
had received the same amount of fertilizer. The only factor tending 
to create a difference in the respective ashes was the amount of 
calcium carbonate in the soil. 

In the table there are three series of comparative analyses — plants 
grown in a sandy soil, in a loamy soil, and in a soil rich in humus. 
In each series there are three analyses — plants grown in the soil 
without calcium carbonate, in the soil plus 30 per cent of calcium 
carbonate, and in the soil plus 50 per cent of calcium carbonate. 

1 J. Konig. Die Untersuchung landwirtschaftlich unci gewerblich wichtiger Stofle. Berlin, 1906, 3. 
ed., pp. 29, 30. 
[Bull. 11] 



35 



The percentages of lime, magnesia, phosphoric acid, potash, and iron, 
in the carbon-free ash are given and also the percentages of these 
constituents and nitrogen in the dry substance of the plant. 

Analyses of the ash of plants grown on sandy, loamy, and humus soils. 

ANALYSIS OF CARBON-FREE ASH. 



Experiment from which 
plants were taken. 


CaCO-j 
in soil. 


Appearance 
of leaves. 


b 

o 

03 
►-1 


O 

03 
O 

0) 


.3 

So 

03 S- 


II 

Ss 

P* 03 


si 

w . 
03O 

PL, 


q 

& 
a 

o 




Per cent. 
[ None. 
\ 30 
{ 50 
1 None. 
I 30 
I 50 
( None. 
\ 30 
I 50 


Green 

Chlorotic 

do 

Green 

Chlorotic 

do 

Green 

do 

Slightly 
chlorotic. 


342 
343 
344 
345 
346 
347 
337 
338 
339 


Per ct. 
11.54 
13.00 
16. 42 
8.80 
13.38 
14.36 
9.76 
9.80 
11.10 


Per ct. 
8.68 
7.09 
8.14 
9.60 
7.99 
6.95 
5.60 
4.89 
4.73 


Perct. 
5.21 
5.42 
4.86 
4.1,1 
4. 74 
4.04 
6.49 
6.65 
6.28 


Per ct. 
48.22 
55.20 
48.10 
44.28 
38.62 
42.61 
55.94 
56.95 
29.37 


Per ct. 
4. 65 
4.22 


II (loamy soil) 

III (soil rich in humus) 


1.86 
2.74 
2.28 
2.20 
3.62 
6.87 
3.02 



ASH CONSTITUENTS IN DRY SUBSTANCE OF PLAN T. 



Experiment from which 
plants were taken. 



I (sandy soil) 

II (loamy soil) 

III (soil rich in humus) 



CaC0 3 

in soil. 



Per cent. 

None. 
30 
50 

None. 
30 
50 

None. 
30 
50 



Appearance 
of leaves. 



Green 

Chlorotic... 

....do 

Green 

Chlorotic. . . 

....do 

Green :. 

....do 

Slightly 
chlorotic. 



>> 

O 


o 


O 

03 

o 


.03 

c o 


ftP-i 


03O 


q 


03 
hi 


£3 


0) 

| 

3 


2a 




a 
o 

i-h 

P.ct. 




P.ct. 


P.ct. 


P.ct. 


P.ct. 


P.ct. 


342 


0.19 


0.71 


0.54 


0.32 


2.99 


0.29 


3«3 


6.43 


.84 


.46 


.35 


3.55 


.27 


344 


9.11 


1.50 


.74 


.44 


4.38 


.17 


3*5 


5.93 


.52 


.57 


.28 


2.63 


.16 


3*6 


6.08 


.81 


.49 


.29 


2.35 


.14 


3+7 


7.45 


1.07 


.52 


.30 


3.18 


.16 


337 


6. 76 


.66 


.38 


.44 


3.78 


.21 


338 


6.68 


.65 


.33 


.44 


3.83 


.46 


339 


8.11 


.90 


.38 


.51 


2.38 


.24 



P.ct. 
0.67 
.55 
.55 
.75 
.58 
.60 
.72 
.67 



It will be seen that the addition of calcium carbonate to the sandy 
and loamy soils, inducing chlorosis, had the effect of increasing the 
percentage of lime in the plant ash and of diminishing the percentages 
of iron. The percentage of magnesia as a rule diminishes, although 
not with the same regularity, while the phosphoric acid shows no 
regular increase or diminution. In the soil rich in humus the addi- 
tion of 30 per cent of calcium carbonate had no effect upon the plant 
ash, and it will be remembered that it also had no effect in inducing 
the chlorosis. The addition of 50 per cent of calcium carbonate to 
this soil, however, induced a slight chlorosis, and affected the plant 
ash, in the same way, although to a less degree as did smaller addi- 
tions of calcium carbonate to the sandy and loamy soils. 

In regard to the percentages of the various mineral constituents 
in the dried substance of the plant, it will be seen that wherever 
chlorosis was induced the addition of calcium carbonate to the soil 

[Bull. 11] 



36 



had the effect of increasing the percentage of total ash in the plant, 
of increasing the lime, and of diminishing the nitrogen. Between 
the chlorotic and green plants there were no regular differences in 
the percentages of phosphoric acid, iron, and magnesia in the dried 
substance. 

From a consideration of these analyses alone it appears, by a 
process of elimination, that the chlorosis is in some way dependent 
upon the content of lime or iron in the ash or upon the content of 
ash, lime, or nitrogen in the dried substance. 

In fields of chlorotic plants growing on calcareous soils there were 
always certain individual plants that maintained a green color longer 
than the others. These plants eventually became chlorotic, but it 
was thought that possibly the ash content of the plants, which had 
not yet become chlorotic, might show some regular differences from 
the ash of plants that were already chlorotic. In the table below 
such comparative analyses are given. The first four analyses are 
of plants grown on a soil containing 3.30 per cent of calcium carbon- 
ate. The next two analyses are of plants grown on a soil containing 
79 per cent of CaC0 3 , and the last two of plants grown on a soil 
containing 33 per cent of CaC0 3 . The analyses are to be compared 
by twos, as in each case the chlorotic plant and check plant were 
grown under the same conditions. 

Analyses of the ash of chlorotic and green plants from calcareous soils. 





Appearance 
of leaves. 


d 

o 

i- 
o 

■s 


Analysis of carbon-free ash. 


Ash constituents in dry substance 
of plant. 


Description 
of plant. 


O 

03 

o 

co 
3 


03 
03 C- 


oC 
■§A? 

PL, 


A 

CO 

Ph 


q 

a 
o 


eg 

CD 

s 

d-d 

o a 

£2 03 

a 

o 


O 

03 

o 

1 
3 


.2 

'cO . 

03 2. 
3 


•Son 
o-d 

£1 


A 
CO 

Ph 


O 

s 

a 
o 


a 

o 


Large Cabezo- 
na, 18 mos. 
old. 
Do 


Green 

Chlorotic 

Green 

Chlorotic 

Green 

Chlorotic 

Green 

Chlorotic 


237 

238 
233a 

233d 

1% 

195 
104 

103 


p.ct. 

27.33 

26.18 
23.16 

24.00 
29.40 

29.45 
23.37 

28.17 


P.ct. 
9.12 

14.19 

6.70 

10.35 
12.55 

9.83 


P.ct. 
5.89 

8.53 
8.54 

5.66 
4.42 

3.45 
4.93 

3.46 


P.ct. 
33.44 


P.ct. 

1.11 


P.ct. 
6.00 

5.33 
5.81 

7.70 
6.28 

7.10 
6.56 

7.81 


P.ct. 
1.64 

1.40 
1.35 

1.85 
1.85 

2.09 
1.53 

2.20 


P.ct. 
0.55 

.76 
.39 

.80 
.79 

.70 


P.ct. 
0.35 

.45 

.50 

.44 
.28 

.25 
.32 

.27 


P.ct. 
2.01 


P.ct. 
0.07 


P.ct. 
0.90 

.71 


Small Cabezo- 
na, 18 mos. 
old. 
Do 


43.72 

29.65 
13.05 

19.78 
35.45 

33.64 


.49 

.47 

.43 

.55 


2.54 

2.28 
.82 

1.39 
2.33 

2.63 


.03 
.04 

.03 

.04 


.76 

.76 


Red Spanish, 

24 mos. old. 

Do 


.91 

66 


Red Spanish, 

14 mos. old. 

Do 


1.47 

.88 







It will be seen from the table that there are no differences between 
the analyses of the green and chlorotic plants that are sustained in 
all four cases. The nitrogen content of the green and chlorotic plants 
is in one case equal but in the other three cases in this table, as well 
as in all the other analyses made, the chlorotic plants contain much 
less nitrogen than the corresponding green plants. 

[Bull. 11] 



37 



Considering all the analyses together, it will be seen that the ash 
of these plants grown on calcareous soils differs from the ash of plants 
grown on noncalcareous soils chiefly in containing a larger amount of 
lime and a smaller amount of iron. 1 

While there were no differences between the chl orotic and green 
plants reported in the table it should be borne in mind that the green 
| plants were exceptional in that they resisted the chlorosis longer than 
the average plant, also, that while these plants were green, they were 
not normally developed and that this class of plants eventually 
became chlorotic (p. 36). 

To see whether the large amount of lime in the ash is the sole cause 
of the chlorosis analyses were made of plants which were grown on 
noncalcareous soils that had received a heavy application of lime. 
The plants were grown on small plats of a clay loam soil, 40 plants to 
the plat. The check plat received no lime; the second plat, lime at 
the rate of 3,400 pounds of calcium oxid per acre in the form of 
burnt lime; and the third plat, the same amount of calcium oxid per 
acre but applied in the form of gypsum and burnt lime together. 
The growth of the plants in the limed plats was depressed, but none 
of the plants ever showed chlorosis. The plants were 16 months old 
when analyzed. In the following table are given the analyses of 
plants from each of the three plats: 

Analyses of the ash of plants grown on noncalcareous soils which had received heavy 

applications of lime. 





o 

o 
o ^ 


6 


Analysis of carbon-free ash. 


Ash constituents in dry substance of 
plant. 


Quantity of lime 




03 


o . 


O 

43 




a> 




03 


o . 


O 




^. 


per acre added 
to soil. 


2§ 

03— ' 
0) 


o 

OS 


O 

03 

o 






q 




O 

03 


o>0 




q 

PH 


a 
s 




Pi 

< 


o 

X! 

03 


1 


03^"' 
3 


OT3 
Ph 03 


o 

Ph 


a 
o 


03 
O 




t*3 
os"-" 


Ph 03 


03 
O 

Ph 



o 


o 








P.ct. 


P.ct. 


P.ct. 


P.ct. 


P.ct. 


P.ct. 


P.ct. 


P.ct. 


P.ct. 


P.ct. 


P.ct. 


P.ct. 




Green. 


268 


12.00 


19.40 


5.96 


53.04 


7.36 


3.19 


0.38 


0.62 


0.19 


1.69 


0.24 


0, 93 


3,400 lbs. CaO 




from CaO 


...do... 


267 


22.32 


25.25 


5.99 


25.68 


6.33 


2.78 


.62 


.70 


.17 


.71 


.18 


.79 


3,400 lbs. CaO 






























from CaO and 






























CaSOi 


...do... 


266 


27.60 


20.79 


6.53 


27.33 


2.82 


3.23 


.89 


.67 


.21 


.88 


.09 


■ Hi! 









It will be seen that the plants grown on the soils to which lime was 
applied contained more lime in the ash and dried substance than the 
check plant and less potash and iron. While the content of iron in 
the plants grown on the limed plats is much less than that of the 
check plant it is nevertheless much greater than that of the plants 
reported in the preceding table (p. 36). The nitrogen is practically 
the same in all three plants. 

1 The analyses in the above table show a higher percentage of lime and a lower percentage of iron than 
any of the analyses reported by J. C. Briinnich. Queensland Dept. Agr. Rpt. 1903-4, p. 76. 
[Bull. 11] 



38 

Comparing the analyses in the last table with those in the preced- 
ing table it appears that the green plants of the last table contained 
as much lime and as little potash as the plants grown under condi- 
tions which induced chlorosis, but differed in containing much more 
iron. 

Analyses were also made of chlorotic plants and of plants that were 
once chlorotic but that had become green by treatment with ferrous 
sulphate. These plants were all grown in soil containing 33 per cent 
of calcium carbonate and, previous to the treatment with iron, were 
all equal in size and equally chlorotic. Two months after the plants 
treated with ferrous sulphate had become green all the plants were 
cut and analyzed. 

The results of the analyses are given in the table below. The first 
two analyses are to be compared with each other and the final three 
with each other, as the treatments with ferrous sulphate were carried 
out at different times in these two cases. 

Analyses of the ash of treated and untreated chlorotic plants. 





o 

<o 
o .' 

03 > 

53 in 
<X> 
ft 
ft 
< 


>> 
y 
o 

§ 

m 


Analysis of carbon-free ash. 


Ash constituents in dry substance of 
plant. 


Treatment of 
plants. 


O 

03 

<J 

O 
3 


03 

tcS, 
c3 w 


■Z6 

8*3 

2 "3 

J3 o3 
ft 


O 

¥ 

03 

O 

ft 


q 

ft 

o 
i-l 

t-H 


a) 
a> 

M 

ol 
o 


O 

03 

o 
3 


03 
03^ 


'Z6 

°ft 

J3 o3 

ft 


O 

W 

03 
O 
ft 


q 
ft 

a 
o 


¥ 

o 

h 




Chlorotic. . 

Green 

Chlorotic. . 

Green 

...do 


255 

254 
276 

277 

278 


P.ct. 
30.10 

20.59 
22.01 

24.52 


P.ct. 
9.18 


P.ct. 

;;. 14 


P.ct. 
37.69 

46.25 

40.40 

42.09 


P.ct. 
0.68 

1.51 
.44 

1 49 


P.ct. 

5.87 

5.63 


P.ct. 
1.77 

1 16 


P.ct. 
0.54 

.34 
.59 

.53 

.68 


P.ct. 
0.18 

.23 
.16 

.18 

.21 


P.ct. 
2.21 

2.60 
2.25 

3.07 

2.55 


P.ct. 
0.04 

.09 
.03 

.11 

.07 


P. ct. 


Brushed with 
FeS0 4 


0.09 4.04 
9.02 2.07 






6.09 1.34 
7.30 1.79 


0.79 


Brushed with 
FeS0 4 


7.25 


2.46 
2.90 


.94 


FeSOi applied to 
roots 


28.76 


9.25 


37.02 


1.01 


• 
6.89 


2.10 


1.39 






The ash of the plants turned green by ferrous sulphate differs from 
the ash of the chlorotic plants only in containing more iron. Thus 
it would seem from this table that the chlorosis is caused merely by 
a lack of iron or by a lack of iron in some active form, and that the 
generally lower content of potash in chlorotic plants is not the cause 
but a result. 

Considering all the facts brought out by the ash analyses, it would 
appear that the chlorosis is induced by an increased absorption of 
lime and a diminished absorption of iron. It is certain that the 
absorption of an unusual amount of lime is not alone sufficient to 
cause the chlorosis. It is possible that when an excessive amount 
of lime is absorbed by the plant that more iron is needed than under 
ordinary conditions. The work of Ililtner on lupines substantiates 
this view. 1 



[Bull. 11] 



1 Loc. cit. 



39 

It is not felt that this conclusion can be stated with certainty 
from a consideration of the above ash analyses alone. If the chlo- 
rosis is caused by the combined effect of an excess of lime and a lack 
of iron in the plant, it would seem that there should be a definite 
ratio of lime to iron in the ash which would induce the chlorosis. 
But in the above analyses no such ratio is apparent. 

It is felt that analyses of other species of plants that become 
chlorotic on calcareous soils are needed for confirmation, and this 
work is now in progress. 

The lower content of nitrogen in the chlorotic plants is probably 
not the cause of the chlorosis but the result. , The absorption of 
nitrogen can hardly be interfered with in calcareous soils, and in all 
the experiments the plants received a liberal supply of easily assimi- 
lable nitrogen. Similarly it appears that the lower content of potash 
found in some of the chlorotic plants of the table on page 35 is but 
the result of the chlorotic condition. In this table it will be seen 
that some chlorotic plants contain 38 per cent, 48 per cent, and 55 
per cent of potash in the ash, quantities much greater than many 
healthy plants contain. These analyses would tend to contradict 
the view held by Sorauer * and some others that the chlorosis on 
calcareous soils is caused by a lack of available potash. 

ENZYMS IN CHLOROTIC AND GREEN LEAVES. 

Woods has shown 2 that under certain pathological conditions of 
various plants, as in the mosaic disease of the tobacco, the attendant 
chlorosis seems to be caused by the presence of an excessive amount 
of the oxidizing enzyms, oxidases and peroxidases, in the leaves. 
Tests were made to see whether in the chlorosis of the pineapples the 
phenomenon was accompanied or caused by a like increase in the 
enzyms. For this purpose the content of normal green leaves in 
oxidases and peroxidases was compared with that of chlorotic leaves. 

The method employed in comparing the different amounts of 
enzyms was as follows: In every case equal quantities (generally 10 
grams) of the fresh leaves were triturated with sand and chloroform 
water in a porcelain mortar. The solution and macerated leaves were 
then made to 500 cubic centimeters with distilled water, allowed to 
stand 15 hours, and passed through a dry filter. The filtrate was 
used in making the comparative tests; 1, 2, 4, 6, 8, and 10 centi- 
meters of these solutions were put in Nessler tubes, the volume of 
each tube made to 10 cubic centimeters with distilled water and equal 
quantities of neutralized hydrogen peroxid and freshly prepared 
2 per cent alcoholic solution of guaiacum resin added to each tube. 
At the end of 10, 15, or 20 minutes the various tubes were compared 

i Loc. cit. 2 A. F. Woods. Centbl. Bakt. [etc.], 2. Abt., 5 (1899), No. 22, pp. 746-754. 

[Bull. 11] 



40 

in regard to coloration or for the amount of guaiaeum oxidized. 
Tubes having the same depth of coloration must contain equal 
quantities of the enzyms, as all the variables affecting the reaction 
between the enzyms and the guaiaeum are fixed. In every case the 
amount of peroxid and guaiaeum, the volume of solution, the tem- 
perature, and the time of reaction is the same. If, then, a tube to 
which 2 cubic centimeters of a leaf extract was added gives the same 
coloration as another tube containing 4 cubic centimeters of a second 
leaf extract, it is evident that the tubes contain equal quantities of 
enzyms and that the first leaf, therefore, contains twice as much of 
the enzyms as the second. 

There is no exact quantitative method for determining the abso- 
lute amount of these enzyms, but the above method gives the com- 
parative quantities with sufficient accuracy to show significant 
differences. 

Tests were first made, taking samples from different leaves and 
parts of leaves of the same plant, in order to ascertain how great the 
error might be in sampling. It was found that two samples taken 
near together on the same leaf, or from the same relative position 
on leaves of similar age, gave duplicate determinations. Also sam- 
ples from similarly situated leaves on different plants of the same 
age gave duplicate determinations. Samples taken from very old 
leaves differed, however, from very young ones. Also a sample 
taken at the base of a leaf differed slightly from one taken near the 
tip of the same leaf. Therefore, in all the following tests, care was 
used to take the samples from the same relative position on leaves 
of similar age. 

From preliminary tests it was apparent that the quantity of oxi- 
dases in pineapple leaves is very small in comparison with the qtian- 
tity of peroxidases 1 and that the quantity of oxidases varies in the 
same proportion as the peroxidases, hence tests were only made for 
the peroxidases. 

The leaves of the plants grown in the pot experiment described on 
page 21 were tested for peroxidases. 2 The results are given in the 
following table, in which the first column gives the soil in which the 
plant was grown, the second the condition of the leaves in regard to 
chlorosis, and the third the quantity of peroxidase. The quantity 
of peroxidase in the leaves of the check plant is taken as 10 and the 
other quantities are expressed relative to this. 

1 By oxidases are here meant those enzyms which blue an alcoholic guaiac solution without the addition 
of hydrogen peroxid, and by peroxidases, those enzyms requiring hydrogen peroxid to give the guaiac 
reaction. 

According to Bach and Chodat and Moore and Whitley we may be dealing here with only one enzym, 
peroxidase; the blueing of guaiac solution without hydrogen peroxid being due to a peroxidase plus an 
organic peroxid. 

' 2 Catalase was also tested for, but found present only in very small and apparently equal quantities in 
the green and chlorotic leaves. 
[Bull. 11] 



41 

Amount of peroxidase present in chlorotie plants grown on soils containing different 
percentages of calcium carbonate. 



CaC0 3 in 
soil. 


Appearance of leaves. 


Compara- 
tive 
amount of 
peroxidase. 


Per cent. 
None. 
5 
10 
13 
17 


Green 


10 

7.5 
10 

8.3 

5 


Slightly chlorotie 

do 




do 





The leaves of the plants grown in pot experiments I, II, and IV 
(see pp. 23-25) were also tested for peroxidases. In these cases leaves 
were taken from two check plants, one from the largest and one from 
the smallest of the five grown. The results are given in the table 
below, the arrangement of which is the same as the preceding table. 

Amount of peroxidase present in chlorotie plants grown on soils containing different 
percentages of calcium carbonate. 



Plants from Experiment I. 


Plants from Experiment II. 


Plants from Experiment IV. 


CaC0 3 
in soil. 


Appearance 
of leaves. 


Compar- 
ative 

amount 
of 

peroxi- 
dase. 


CaCOs 
in soil. 


Appearance 
of leaves. 


Compar- 
ative 

amount 
of 

peroxi- 
dase. 


CaC0 3 
in soil. 


Appearance 
of leaves. 


Compar- 
ative 
amount 

of 
peroxi- 
dase. 


Per cent. 

None. 

None. 
20 
30 
40 
50 


Green 

do... 

Chlorotie 

do 

do 

do 


10 

10 
2.5 
6.6 
3.7 
3 


Per cent. 

None. 

None. 
20 
40 
50 


Green 

do 

Chlorotie 

do 

do 


10 
10 

5 

8 

4.5 


Per cent. 

None. 

None. 
10 
30 
30 


Green 

do 

Chlorotie 

do 

do 


10 
10 
6.6 

6 

7 

















In the next table is given the peroxidase found in a chlorotie plant 
and in two plants that were once chlorotie, but that had become green 
by treatment with ferrous sulphate. The plants were all growing in a 
sand containing 34 per cent of calcium carbonate, and previous to the 
treatment with ferrous sulphate were equally chlorotie. It will be 
seen that although one of the plants treated with iron contains much 
more peroxidase than the other, they both contain more peroxidase 
than the chlorotie plant. 

Amount of peroxidase in treated and untreated chlorotie plants. 



Treatment of plants. 


Appearance 
of leaves. 


Compara- 
tive 
amount of 
peroxidase. 


Untreated 

Brushed with FeS0 4 


Chlorotie 

Green 

do 


3.3 
6.6 
10 





[Bull. 11] 



42 

The results of these determinations agree in showing that green 
leaves of pineapple plants contain much more peroxidase than chlorotic 
leaves. It is apparent, then, that this chlorosis of pineapples growing 
in calcareous soils is caused by a different disturbance in the plant 
from that in those cases explained by Woods. Woods examined 
chlorotic leaves from many plants. Some of these yellow leaves had 
been punctured by aphids. The colorless portions of variegated 
leaves, etiolated leaves, tobacco leaves affected with mosaic disease, 
and peach leaves from trees affected with "yellows'' and rosette were 
also examined and found to contain more oxidizing enzyms than nor- 
mal green leaves. Although the chlorosis, or lack of chlorophyll, in 
all these cases was attended by an increase in oxidizing enzyms, it is 
evident from the above results with pineapples that the chlorosis of 
leaves is in some cases attended b}" a diminution of peroxidase. 

In the light of the other work on the pineapple leaves it is probable 
that this deficiency of enzyms in the chlorotic leaves has no bearing 
on the chlorosis, but is merely the result of the degeneration caused 
by the excess of lime and lack of iron in the plant. 

EFFECT OF LIGHT ON THE CHLOROSIS. 

It was observed in the field that plants growing under partial shade 
seemed less chlorotic than those exposed to full sunlight. To see if 
the chlorosis could be much diminished by partial shade a dupli- 
cate of experiment I (see p. 23) was run in a glass house that was 
heavily shaded. 

The plants in the glass house showed very much less chlorosis than 
those exposed in the open. The results of this experiment are incon- 
clusive, however, as the plants in the glass house did not make half the 
growth of those exposed in the open. Since the intensity of the 
chlorosis has been seen to be more or less dependent on the amount of 
growth, the smaller degree of chlorosis in this case was probably due 
to the fact that little growth was made. 

It was found, however, that plants which had become strongly 
chlorotic and which had long ceased to grow, became decidedly 
greener when placed under heavy shade for one or two weeks, but 
when they were again exposed to full sunlight they showed their 
original chlorosis within a few days. 

The explanation of these facts is apparent. It has been shown that 
there is a continuous formation and destruction of chlorophyll in the 
plant. 1 The destruction of the chlorophyll is brought about by strong 
sunlight and increases with the intensity of the light. In the chlorosis 

■H. Euler, Grundlagen unci Ergebnisse der Pflanzenchemie, Braunschweig, 1908, pt. 1, p. 193. F. 
Czapek, Biochemie der Pflanzen, Jena, 1905, vol. 1, pp. 452, 453, 468. H. Molisch, Ber. Deut. Bot. Gesell, 
20 (1902), pp. 442-448. Molisch found that aloe leaves that became brown in direct sunlight became green 
again when placed in the shade. 
[Bull. 11] 



43 

of pineapples in calcareous soils the plant is unable to form the chloro- 
phyll as fast as it is destroyed by the light. When the plant is 
partially shaded, however, the balance of the reaction is shifted; the 
chlorophyll is destroyed less rapidly, though it may be formed at the 
same rate as in the sunlight, so the plants become greener. 

The appearance of less chlorotic plants in shaded portions of a field 
affected with chlorosis is, then, due to the fact that the plants have 
made a less rapid growth at the start than the rest of the plants, and 
also to the fact that the chlorophyll is destroyed less rapidly in the 
shaded plants. 

CONCLUSIONS FROM INVESTIGATIONS OF THE CHLOROSIS. 

In deciding as to what is the primary cause of the failure of pine- 
apples on calcareous soils and of the appearance of the chlorosis, it 
should be borne in mind that chlorosis is not a specific disease, but is 
merely an outward manifestation that attends certain physiological 
disturbances in the plant. Plants suffering from poor drainage and 
from bacterial diseases and certain plants growing on calcareous soils 
all show chlorosis. It should also be taken into consideration that 
one disturbance in the physiology of the plant will bring on a series of 
other disturbances, which are to be regarded only as attendant 
phenomena. 

In the abdVe investigations it was found that pineapples, in common 
with some other plants showing chlorosis on calcareous soils, were 
greatly benefited by treatment with iron salts, the iron salts over- 
coming the chlorosis and inducing a normal growth. 

No other treatment was found that overcame the chlorosis. It 
appears, then, that the plants need iron and that they are Unable to 
obtain this from the soil, although there is a large percentage of iron 
in some of the calcareous soils. The facts that solutions of ferrous 
sulphate applied to the soil gave no result, while crystals applied to 
the roots or solutions of iron applied to the vegetative portions of the 
plant gave marked improvement as soon as they were absorbed, show 
that the carbonate of lime in the soil reacts with the iron (forming 
ferric carbonate) and depresses the availability of the iron for the pine- 
apple plant. That all species of plants growing on calcareous soils 
do not suffer to an equal degree for lack of iron is probably because of 
their different abilities to take up iron. That certain species of plants 
differ in their ability to take up phosphoric acid is well known. 

The ash analyses support in a general way the assumption that 
there is a lack of iron in the chlorotic plants and show that probably 
the increased absorption of lime creates a necessity for an increased 
quantity of iron. The excessive amount of lime in the plant may 
render inactive the small quantity of iron absorbed. 1 With our pres- 

1 See also Hiltner v Loc. cit. 
[Bull. 11] 



44 

ent knowledge of the mineral nutrition of plants such an assumption 
is, of course, only speculative. 

The facts that neither a merely alkaline soil nor a soil containing 
much assimilable lime induces chlorosis, but that a soil which is at the 
same time alkaline and contains much easily available lime (as a cal- 
careous soil) does induce chlorosis, lend credence to the above view. 
In a soil alkaline with sodium carbonate there would be a depression 
in the availability of the iron, but not an increased absorption of lime. 
Plants grown on a soil containing gypsum absorb an increased amount 
of lime, but there is no depression of the availability of the iron on 
such soils. Plants grown on a soil containing calcium carbonate, 
however, absorb an unusual amount of lime, and because of the depres- 
sion of the availability of the iron absorb but a small amount of iron. 

That chlorotic plants contain less nitrogen and less peroxidase than 
green plants is probably because the nutrition has been disturbed by 
the increase of lime and lack of iron. The lower content of nitrogen 
and of the oxidizing enzyms are, then, not primary causes of the 
chlorosis, but rather results of the degeneration produced by the lack 
of iron. This view is strongly confirmed in the preceding work by 
the fact that treatment of chlorotic plants with iron increased the 
nitrogen and peroxidase content. 

Although but little attention has been paid to the iron requirements 
of plants, Molisch 1 has shown that iron exists in all plant organs, 
mostly in organic combination, and that seeds contain iron stored up 
in the globoid bodies of the aleurone grains. While iron is not a con- 
stituent of chlorophyll, it seems to be necessary for the formation of 
chlorophyll, since plants grown in iron-free solutions become chlorotic. 

It seems, then, that pineapples growing on calcareous soils absorb 
an excessive amount of lime and an insufficient amount of iron; that 
as a result there is an inability to form chlorophyll and degeneration 
of the plant follows, as is shown by a decrease in the content of 
peroxidase, nitrogen, and occasionally potash. 

SUMMARY. 

Pot experiments and a chemical survey of the pineapple soils of 
Porto Rico show that the failure of pineapples, with the appearance 
of chlorosis, on certain areas is due to an excessive amount of car- 
bonate of lime in the soil. 

For ordinaiy sandy soils about 2 per cent of calcium carbonate 
renders them unsuitable for pineapples; smaller amounts than this 
do not appear to be injurious. 

Soils composed principally of organic matter may contain about 
40 per cent of calcium carbonate and still produce vigorous plants. 



1 H. Molisch. Die Pflanze in ihren Beziehungen zum Eisen. Jena, 1892. 
[Bull. 11] 



45 

Pineapple plantings on calcareous soils should be abandoned and 
the land planted to lime-loving crops. 

In curing the chlorosis, fertilizers were ineffective, but treatment of 
the leaves with solutions of iron salts or crystals of ferrous sulphate 
applied to the roots was effective and induced a normal growth. 
This treatment does not appear to be commercially feasible. 

The chlorosis is not caused by an organic disease, but is the result 
of a disturbance in the mineral nutrition of the plant induced by the 
calcareous character of the soil. 

It is neither the mere alkalinity of calcareous soils nor the large 
amount of assimilable lime that causes this disturbance, but the 
combined action of the two properties. 

The disturbance in the mineral nutrition of the plant, or the primary 
cause of the chlorosis, seems to be the lack of iron in the ash or the 
small amount of iron in the presence of a large amount of lime. A 
mere high percentage of lime in the ash does not induce chlorosis. 

Chlorotic leaves are lower in nitrogen and oxidizing enzyms than 
green leaves, due, probably, to the degeneration induced by the lack 
of iron. 

Strong light increases the chlorosis by the more rapid destruction 
of the chlorophyll. 

ACKNOWLEDGMENT. 

The greater part of the analytical work detailed in this bulletin was 
performed by Mr. W. C. Taylor. 

Thanks are due to various planters who kindly sent soil and plants 
necessary for the work, and to Mr. Lucas Valdivieso for 15 tons of 
limestone used in the experiments. 

[Bull. 11] 

o 



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